I've never comprehended MS's fad fetish. The current thing is to make every user interface look and feel like a web page. Who in the *(&% thinks that's a good idea? Since when is HTML the be-all, end-all of user interfaces?
Similarly, the idea of making the whole O/S and all apps live and breath in .NET-land is ludicrous. It will be yet another opportunity for Linux to outperform Windows. The slow performance and unbelievable code bloat that would necessarily accompany such an architecture would simply be laughable.
This started a few years back when M/S was worried Netscape would 'take over' the desktop. M/S went a bit overboard (as is their wont) and proceeded to weld IE into the O/S. Ultimately not a good idea both from the UI side, as you mention, and the O/S code maintainability side.