Agree with you that tooling was abysmal but all of those *nix had their bright flowering that subsequently pollinated other *nixes. AIX service management (SRC I think?) eventually saw life in Solaris as SMF. BSD jails reborn as containers. The HP-UX had batch job management that was very good. Solaris ABI/API compat between versions was exemplary, you can count on the OS upgrade not breaking your application. When the compiler was still being sold (thousands of dollars by the seat license), it was optimized for the SPARC processor and outperformed same code compiled by the GNU compiler. I wish we had all of that still.

Apropos of the "curated App Store" or "free-for-all" discussion currently active, I remember talking to a colleague in the early 2000s that Apple with its curated BSD-derivative OS was exactly what open sourced OSes needed. Users don't want to do more work than necessary; in retrospect, the selling point that users can do anything+everything with *nix OS was the wrong message.

You didn't mention package management and network booting to be pain points. They were nightmares, which Linux eventually solved. I think that's where the race was lost.