Harmonix could call it "Indie Rock Band"
1. At 800 songs, the DLC list is already pretty unwieldy to browse, expecially using instruments. If we're about to get flooded with thousands more songs, it will become a nightmare. The whole browsing interface needs to be re-worked (and while you're at it, add "What's Hot" and "Staff Picks").
2. Most of the stuff on RBN will be un-heard of. I'm not going to pay 160 MS points to try out some unknown song. The one-time purchase price of the disc should allow users to download songs at no additional cost. Like Zune or Nokia's Comes With Music.