Ok, you only miss what SIMPLE mean.
Do one thing and do it well.
Merging two tools is not simple. It is neither elegant.
Freebsd-update
is a good tool, simple, elegant, with a clear scope and so on.
Pkg
is in that philosophy too.
Merging this two simple, easy to use tool into one with more options, more steps (need I a reboot and relaunch the tools to finish my upgrade ?) and a not well defined scope is not SIMPLE, not the Unix way.
I know in the Linux world, SystemD need to do all things. Ubuntu want to package all update in the same way and so on.
But the result is not simple. The emerging tool seems to be simple, (one click), but who really undestood what a major update in Ubuntu will do ? It always break my system for information. And I never know why.
(The list of things installed in a Xubuntu linux is huge...)