I suppose Google needs the Play store to include music and movies if it is going to compete in the tablet space with the iPad. You can't have salespeople saying "Well, yeah, true, with the iPad you can buy movies and music on iTunes, but look! Angry Birds!" My problem is that competing app stores that use DRM make for some very bad situations for consumers. If you have some music from iTunes and some from Google Play, you're basically screwed already.
What we need instead is for the sync, backup and catalogue management for user accounts to be a separate service - the equivalent of retail in this online digital world. Then Apple, Google and whoever else is free to sell their apps, music and movies through their stores, but consumers get a choice of third-party providers for backup and sync functionality. They can buy freely from any of the other distributors and have their purchases show up in that third party account, ready to sync to whatever device they use, without DRM, and freely able to move to any competing service at any time.
Mokalus of Borg
PS - I have the same dilemma with my ebooks.
PPS - I know I said I wouldn't buy ebooks, but they're just so cheap.