It's understandable that you should generally keep the UI the same between releases, it shouldn't be changing every release.

But at some point in a 20-year development cycle you might want to switch things up, and a major release is the time to do it.

I don't think anyone had a legitimate complaint when Blender completely revamped their UI a few years ago. It was objectively better, and "it's different than what I'm used to" was not a valid complaint.