Depends. What Flash and Silverlight do is just as bad => This proposal isn't worse.
But Flash and Silverlight are dead or dying and were never public specifications we cared about. What I consider 'worse' here in this proposal is that we'd kind of 'bless' the DRM layer in HTML. I fear a comment like "Hey, it's part of HTML 5 so it has to be good, right?" if nonsense like this is added.