I'm sure Microsoft would happily claim that "changing our DRM software might introduce new weaknesses that allow users to 'steal' content. Then the sky will fall." After all, Microsoft cares more about money than the users' security. It has taken them till just a few years ago (or maybe it was earlier this year, I can't remember) to disable SecuRom, another video game-oriented form of DRM that was baked into Windows against the wishes of many users.
If the vulnerability hasn't been fixed yet, chances are it's not ever going to be fixed. Hopefully, Microsoft will cease Windows Media Player's DRM for good, since that's the only way I can see users being protected from this kind of abuse.