From Core Mobile Web Platform Community Group
Enabling some form of DRM protection unlocks a whole category of apps (such as Netflix, Spotify, etc.) which otherwise cannot be built on the Mobile Web Platform.
Although many disagree with the idea of DRM, there seems to be industry-wide consensus that some form of content protection is necessary.
The main point of contention is about where in the stack it's best enabled.
Google, Microsoft, and Netflix drafted a spec proposal not long ago, which was immediately teared down in flames by Mozilla.
This is one of the areas where we have the least information. The W3C Web and TV Interest Group is also working on this. Syncing up with them would be a good first step.