I agree, at least an option to have more granularity would be a good thing. Maybe the upcoming changes to Android/iOS permission models will solve the problem of UI/UX and this will finally become fashionable.

However, there is also a question of properly enforcing granular per-process restrictions (without breaking backwards compatibility). It's not a trivial task, there are plenty of corner cases: race conditions, symlinks, alternate data streams, process hollowing... I don't expect any implementation to be full-proof in the first decade.