In all cases, there are numerous complete third-party applications that provide a broad range of support that is properly licensed.
IOW crapware may be preinstalled by the OEM that supports DVD playback. One of the divisions at the company I work for produces computer based training. Much of the content is still sold on DVD even though it's also available on-line. Going forward we have no guarantee that a W8 PC equipped with a DVD will be able to playback the content on our DVDs. Furthermore we now have to support the vast array of crapware DVD players out there rather than having a standard (WMP).
Based on the above discussion, it should be clear that we cannot enable DVD playback all the time in Windows Media Player.
IOW, in case it hasn't registered with you yet you fool, we have decided DVD is dead along with WMP and thus will not ship the full WMP experience found in W7 but instead will purposely gimp WMP in order to serve our agenda (to be like Apple).
With this attitude unless W8 is a huge hit (and not be default because it's shipped on every PC) Microsoft is going to find itself on the Island of Misfit Toys except without any friends. I'm so glad I don't work there. It's gotta be down-right embarrasing.