I guess most of us did this. Coding on Windows inside Visual Studio
I tried that back in 2003 when I started my web dev company until I was screwed by Microsoft and the updated asp.net. Switched to FreeBSD and have not touched Windows since (at least mostly true). So, no, I don't think most of us do it that way cause I haven't met anyone doing software development not for Windows on a Windows machine.
lack of a usable User Interface in *NIX world
I haven't a clue what you mean by that. After 12 years, this has never been an issue for me or any company I have ever worked for. The few times I've had to work on a Windows machine for a client, it has always been heartache and frustration. I would never consider developing anything on a Windows machine and have turned down work when asked to do so.
lack of affordability of OS X
I am heavily involved in the entertainment industry. Nowadays, I deal with a lot of small theatre companies that have no money. Despite that, they all use Macs for in-house work. I have a tough time with statements about the cost of OSX or Macs when these kids and companies all have a Mac.
At one time, Macs were rated #1 by Consumer Reports for reliability and usability and service for more than 10 years in a row. That is something worth paying for.
That said, I have no clue why anyone would use a Mac as a server but I entirely understand why they would use one as a workstation. Also, I want to note that I build my own workstations and servers. I have never owned any Apple gear except an original iPad I was given for Christmas but no longer use it. My son, a Windows-only user for years and now a theatre company owner, bought a Mac, two iPads, and and iPhone on his own with his own money, no prodding from me, and doesn't know how he would exist without it. The cost, he claims, is well worth it cause everything works together and with everything he needs to connect to, both hardware and software.
I hope I didn't go off topic.