Then Microsoft comes along and changes everything. The Ribbon instead of the pull down menus. Now which office suite works more like what users have used for a couple decades?
Windows 8 comes along with a totally different UI. So different that ordinary users don't know how to do the most basic tasks like print, or even how to shut down the computer.
Windows 8 UI (no matter what you call it) "fixes" things by adding back a start menu, but not calling it start.
No search box in the start menu -- you just have to magically know that you can start typing.
And magical key combinations to type in commands.
IMO, it really is change for the sake of change. And generally change for the worse. The interface we had with classic Mac, and Win 95 was pretty usable. And stable. (Nevermind the underlying tech it ran on top of, no real kernel, etc.)