Color is used an out of band way of adding more information to a standard 2D output. Same with bold / underlines characters when on an "extended" terminal.
Really we just need 3D computer terminals and we would be able to keep to the monochrome goodness.
You made a valid point here, 3D monochrome does seem more useful... however it will never be used by professionals (military, airports, transportation, medical, planes, cars... etc). It will be used maybe for unimportant things, like knowing the price tag of an Apple laptop while at the computer/electronics store.
Heres the thing, adding color into the equation is like quantum computing.
Humans will have more information/states that can be used to identify as syntaxes or meanings in conjunction with physical unique symbols/characters.
Matter of fact adding symbols/characters is rather considered nothing more than spam information.
Imagine you are trying to find the text: "function_something()".
And you put like a bunch of lines like this to find it: ---------------------------------
Good luck finding it when many functions or spam lines like that exists in the code file.
Imagine adding color in conjunction with that particular function and different functions have different shades of color or different color entirely. People who can utilize this new skill in parsing information will be far more advanced and productive than programmers still using monochrome style blinded/blurred by "color".
The analogy is like using a car to travel to work but get stuck in traffic as compared to using a helicopter (use the helicopter since it's better).
But thats not all, here are more reasons why using colorized texts is crucial for programming (specially for those who codes for mission critical/safety applications). I'll give
scientific reasoning to why this is the case below:
The human eyes are also highly sensitive to certain colors than simply unique symbols/characters. Theres a whole science in this and it is seriously utilized and taken seriously. Why do you think military's state of the art intelligence and warfare equipment are deliberately, specifically and scientifically engineered to use colors on the displays so that it can drastically help the operators/users and also prevent enemies finding them?
You think all those military movies are nothing but hollywood fantasy in adding color to the command room, sonar/radar screens, navy ship control deck, air force cockpit, submarine control room and airport control towers? You think all of these colors added into these military/professional computer devices/equipment is so that kids can go have a disco party?
Here is the perfect
scientific proof why advanced programming (specially for mission critical/safety applications) needs "colorized" texts/symbols and should be a legal standard. All the way back in 1958 a paper was written of the precise problems of crappy room lighting and improper colors used on CRT screens for military. It's literally explaining that using different and precise colors for room lighting and CRT monitors are more meaningful and productive.
Just read the first chapter overview if you're not convinced:
"The illumination requirements of the two groups of people who must jointly use a radar center (operations personnel, and maintenance and other personnel) differ radically. The requirement of both groups cannot be met by ordinary lighting procedures. Under ordinary conditions, light which is needed by supporting personnel to do maintenance, etc., destroys most of the information available on a phosphor cathode ray tube (CRT) display and greatly diminishes the ability of the radar operator’s eye to use the information that remains. The sensitivity of the human eye to light of different frequencies, and the frequency characteristics of the light energy emitted by the phosphor of a CRT display must be fully understood to appreciate the nature of the radar room lighting problem."
Here is the link to the PDF paper:
Reference: https://etd.ohiolink.edu/apexprod/rws_etd/send_file/send?accession=osu1486472030898113&disposition=inline
Hmm... still not convinced? I got more scientific and professional facts why "colorized" texts/symbols/screens is better, safer and productive. I have another paper as proof from the US DOT (Department of Transportation) discussing about ATC (Air Traffic Control) displays to support my claim.
Here is what is mentioned in the first chapter of the paper:
"Color is an effective and attractive tool for coding information on a display. It can help to organize and categorize complex information and can also have a profound effect on our ability to search for specific information. Color is both attractive and functional."
Here is the link to the PDF paper:
Reference: http://www.tc.faa.gov/its/worldpac/techrpt/ar-99-52.pdf
Alright, you still might be scratching your head now, still not convinced and confused why scientists/engineers have never used color or made a standard for it in computer science/programming.
However, here is what the "US Naval Submarine Medical Research Laboratory" have to say about "colorized texts/symbols" for US Naval Undersea (submarines) control center systems, a paper released on 1984.
Below are some things mentioned in the
scientific paper:
"color coding can offer many advantages when used properly. Its most useful application is to visual search, although it is an effective way to organize information on various types of displays."
"The six colors recommended for use on SUBACS displays are red, yellow, green, cyan (blue~green), blue, and white. Previous work has shown that no one size of color set is best for all possible CRT applications. The optimal number of colors in a display depends on the specific task. This color set was limited to six, because, in SUBACS, it is desired that different colors be used to categorize different types of information, although they will be used redundantly with other codes. The color of a piece of information will, along with the other codes, convey the meaning of that information. Therefore, it is advantageous if the operator can not only discriminate the colors when seen side-by-side"
"ADVANTAGES OF COLOR CODING
Search/Identification:
Superior for finding a particular item of random location on a display
Superior to size, brightness, shape coding on identification tasks
Helpful for counting members of a class and locating information
Attention/Recognition/Memory:
Focuses attention
Effective for coding low probability or very important events
Useful for alerting operator to a change in status
Superior for process control and monitoring
Speed of recognition increased for contrasting colors
Increases retention of information
Information:
Increases information content; provides additional dimension to
display
Acts as a "chunking" unit to organize information, separate categories
Need only a small number in most applications
Learning:
Natural association of certain colors with well known physical states
Speed, ease of learning & comprehension; requires littte additional
training
Vision:
Awareness of color common to all color normals
Improvement of visual acuity from color contrast at low luminance
contrasts
Enhances contrast
Coding:
Superior for areal coding, as in maps
Beneficial as a redundant code
Preference/Aesthetic:
Generally preferred as less monotonous, producing less eye strain
and fatigue
Has known aesthetic properties
Display Design
Allows for reduced display brightness
Reduces display clutter
Practical to implement
Colors effective under wide range of broad-band ambient lighting conditions"
Reference: https://apps.dtic.mil/sti/pdfs/ADA148924.pdf
Alright that submarine paper above already proves why color coding is scientifically useful, hence it can be said that it is also useful in computer programming. Note, I am not saying that color coding is by all means the holy grail for programming, just saying that when programmers say "color coding is effective and helpful", please keep in mind that they know what they're talking about and its simply based on facts. Deliberately saying that the conjecture of color coding is useless by all means and will always cause blurriness/dizziness is grossly wrong and false propaganda.
I have more evidence why color coding is crucial for computer displays for professional usages mentioned below.
Here is what The National Weather Service (NWS) mentions why "color" is so important for parsing information and people who are "blinded" by colorized texts are seriously weird:
"By their nature, radar images use color as a means of communicating information. This can be a problem for people with color vision deficiency. Visolve is a software application (free for personal use) that transforms colors of the computer display into the discriminable colors for various people including people with color vision deficiency, commonly called color blindness."
Reference: https://www.weather.gov/jetstream/refl
The reason why humans are able to avoid getting wet during a bad weather or killed during an incoming storm, its thanks to weather radar systems displaying color. The scientists who sits all day at their desks looking at the computer monitor (just like programmers) uses "color" to help them to "parse" the activity of storms:
Here is a quote from National Oceanic and Atmospheric Administration (NOAA) for the National Severe Storms Laboratory (NSSL) radar system:
"Inside the control room of the experimental Doppler weather radar at NOAA's National Severe Storms Laboratory (NSSL) in Norman, Okla., the storm showed up as a
color-coded mass on the radar's television screen."
Reference: https://vlab.noaa.gov/web/nws-heritage/-/introducing-nexrad
Here is what the US military do to color code different aspects or variables on their Military Map:
Red - Classifies cultural features, such as populated areas, main roads, and boundaries, on older maps.
Brown - Identifies all relief features and elevation, such as contours on older edition maps, and cultivated land on red-light readable maps.
Green - Identifies vegetation with military significance, such as woods, orchards, and vineyards.
Blue - Identifies hydrography or water features such as lakes, swamps, rivers, and drainage.
Other - Occasionally other colors may be used to show special information. These are indicated in the marginal information as a rule.
Red-Brown - Indicates cultural (man-made) features such as buildings and roads, surveyed spot elevations, and all labels.
Black - Indicates cultural (man-made) features such as buildings and roads, surveyed spot elevations, and all labels.
Reference: https://www.boisestate.edu/sps-militaryscience/current-cadet-corner/colors/
Even
certain cars/trucks/buses/planes/ships are "colored" to a precise color not because of just random choice. Scientists and engineers add specific colors to things so that monochrome programmers who gets blinded/blurred with colorized texts would pay attention to certain colors regardless of what they personally think about it. The fact is that your eyes and brain alerts you about it even when you're not aware of it consciously since these acknowledgement events happens subconsciously:
Don't believe me? Here is a professional Japanese Optics Manufacture (Olympus Corporation) have to say:
"In recent years, consideration of human color visual sensitivity has led to changes in the long-standing practice of painting emergency vehicles, such as fire trucks and ambulances, entirely red. Although the color is intended for the vehicles to be easily seen and responded to, the wavelength distribution is not highly visible at low light levels and appears nearly black at night. The human eye is much more sensitive to yellow-green or similar hues, particularly at night, and now most new emergency vehicles are at least partially painted a vivid yellowish green or white, often retaining some red highlights in the interest of tradition."
Reference: https://www.olympus-lifescience.com/en/microscope-resource/primer/lightandcolor/humanvisionintro/
Even the invention of the first
monochrome CRT television is immensely colorized with just white and black color. You might think I'm talking nonsense, but the fact is that the CRT television would never be a proper TV without using many different "shades" of color(gray). So ask yourself, is it not monochrome TV "colorized"? (Answer: It is).
Because of colorization, humans are able to get much more information just from two colors and varying the intensity among these two colors.
Reference: Of how monochrome TVs work, scroll to 8:44 timestamp which discusses about the shades of gray:
View: https://www.youtube.com/watch?v=_Ivc95tsfOU
With just using two colors of white and black and varying the intensity, humans are able to distinguish 1,000 different shades of gray (AKA color):
Reference: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3043920/
However, sadly, for CRT monitors for computers in the old days were rather not advanced like televisions. This is due to limited hardware, and the texts displayed are simply dead on two colors with no additional shades of color in between without varying the intensity of the two colors. This could be maybe programmers/computer engineers/computer scientists did not care for more advanced colorized texts which are used in a more professional environment such is airports, planes, military etc.
Time have changed over the decades and today, there is a great need for colorized texts, its benefits are obvious for programmers and this is nothing more than human evolution for more complex and intelligent ways to be better in programming which is literally a huge factor for advanced computer science.
So parsing through many lines of code, you'll have a higher chance of missing unique symbols/characters or put more effort in finding it as compared to finding colored texts/symbols.
I mean, yes you could say you can train yourself intentionally for months or years to defeat human's gift in evolution to see color and have precise sensory sensitivity for it, but thats like degrading your ability to not make use of it.
With this said, scientifically, it seems silly to program literally with just monochrome (even without different shades of color for it). The the scientific facts and proof are given, color texts/symbols in programming is useful and productive. Does not mean it should be used for everything but needs to be acknowledged that colorized texts/symbols are valid instead of blindly disapproving it.
should have some "word detection" heuristics, but it seems it just assumes "only one change per line" 
