Personally, I cannot abide OSes that force a UI upon me and leave me no choice (which is why I stick to Win7).
The many distros of Linux have amply demonstrated that the UI is easily configurable and has no real ties with any background process. We have today computers that are a million times more powerful than what we had last millenium, but Linux has had configurable UIs since way before Y2K.
There should never be any "change in the UI". There should only be "new options for the UI" that I can enable or not. That is a lesson that Microsoft still has great pain to comprehend.