The thing that's prevented me from going from Win 7 to win 8 is the lack of native Bluray support.
That's also the reason I have Win 7
Going back a few years there was only the one OS which supported the HDCP protocol and Bluray playback that was available at the time, that was a MS one, XP.
Only trouble was, back then there were few pieces of software (PowerDVD and WinDVD) that would play Bluray.
The landscape may have changed a bit since then, but it still remains that the MS platform was there with Bluray support via third party software when it wasn't around on other OS's.
Why it can't be part of the Media centre add-on bundle for Win 8 I don't know.