Bottom line, you don't need to force interface changes on users, and you shouldn't. "Skins" was a concept developed nearly 20 years ago already.
Consider the QWERTY analogy. It's what users want, and it's what users buy, because they are personally invested in the interface.
OS = functionality + interface. These two parts could be provided by completely different vendors. People should have the CHOICE to retain their existing interface.
There are real advances in productivity and usability which have been invented by smart guys over the last 30 years and they are being thrown away by this monstrosity.
Every world-dominating company finally hits a moment when they think their market is their property and they can do what they like with it. And then we move on from them.