I really wish they'd just release a pack where you buy the controller/"instrument" bits, and a disc that has the core game but no actual songs on it. Instead, all the songs are DLC, this core pack includes a coupon letting you download X number of tracks.
But that's just because of all these guitar hero and rockband games, with what, like 20-30 tracks on each edition? There's never more than half a dozen songs on any one game that I actually like. Combined, over the whole series, there's enough to make 1 game I could really enjoy.