These transitions are never fun but they happen sometimes. No API is eternal and it seems a little overwrought to be 'not trusting' Apple because they ditched an API (and entire OS) once, nearly 20 years ago.
I think you have to see before you raise and each of these APIs has changed in incompatible ways over its lifetime. With the possible exception of POSIX which is more of a standard/serving suggestion of slightly-incompatible implementations to begin with.
We can argue how useful those versions of Wordpad and Paint are, especially with modern file formats, but they are usable. I won't blame you for disagreeing with xterm, but over 30 after it was first shipped it's still the closest thing to a standard terminal, and the UI is decent once you get used to it (and much like emacs, it's partially jarring at first because it predates some expectations).
