Dr. Evil explains:

http://blogs.msdn.com/b/b8/archive/2012/05/03/making-windows-media-center-available-in-windows-8.aspx

Just a reminder, if your PC has an optical drive when you buy it or when you buy a retail optical drive, it will almost certainly include DVD playback software and license (unless the drive is sold to be used only as a data drive).  There is little chance a mainstream retail PC is made available with optical drives that do not have the option of DVD playback.

Who cares? Wasn't it once Microsoft's goal to reduce the amount of pre-installed bloatware? And now you need again pre-installed crapola to play a DVD? Just don't forget, we're talking about frigging DVDs here! As much as I bashed Sinofsky and Windows 8 on these forums, I never expected they will go as far and kill such basic functionality.

Dr. Evil also forgets some user scenarios here, like, what if you want to do a clean upgrade from Win 7 to Win 8 and the PC maker didn't deliver any DVD playback software, since the codec was already available in Win 7.

Anyway, what's next? Installing Winamp again for MP3s while we're at it?