For me the good old days were the time spend with Amiga 500, discovering the world of Smalltalk, Oberon and all Xerox PARC research and other pioneers.
I got into UNIX via Xenix, and used almost every commercial flavour of it, but don't consider it the good old days.
The fact that POSIX is stuck in a PDP-11 world, is a proof that no big in the industry, with power to drive POSIX forward, is seeing as a relevant OS API for anything besides writing daemons and CLI applications accessible via SSH.