Along with tight integration, Microsoft is looking to broaden the reach of its DRM technology. That means controlling access to subscription-based media and possibly the type of media that can be viewed or listened to on your digital media player. The key will be how Microsoft treads the thin line between Fair Use and DRM. On the other hand, if WMP 10 will let me sync my music library to my laptop and convert it to a lossy format on the fly, much can be forgiven.
That thin line is the interesting point. I suspect I would define that line as being a lot closer to “it’s my music, give it back” than MS and tbe RIAA would, especially given the RIAA’s approach to these things—as Ars Technica point out, “if someone finds they can’t make a copy for their kid so he can play it in the car, you’re going to have a lot of people returning broken CDs.”