Usually the observation that “a widely used thing is objectively bad” is strong market signal for entrepreneurial opportunity in a big tam.
I for one would welcome a set of deeply integrated ui improvements in a Mac that included a better file manager, better window management, better desktop search, a contact manager just that worked, a messaging client that just worked, audio and camera controls that just worked, a calculator that didn’t suck, etc.
I’d pay at least $100 a year for that tool set.