But software that offers all the features a user will need under a big umbrella with unified UI and UX is much better than "this program uses different syntax because it came from Unix and not GNU"

Yes and no.

A consistent UX is definitely a major bonus, but not if it comes at the cost of oversimplification. If the program gives me an experience gift-wrapped and with a nice little bow on top, but only gives me that kids' gloves experience, it becomes a much worse experience when you need to do anything outside the happy path.

Imagine trying to script git workflows without access to any of the plumbing commands like rev-parse, rev-list, and format strings. You would have to parse the output of git log and git show, hoping that they don't introduce a new change to the output—a much worse experience.

All parts of a program should do one thing well and communicate with other modules over a simple, common interface.

Fun fact: you basically described dbus.