Add content, stop buying updates.
The world as we know it, being haunted by the usual ghosts of economy and meh. Out comes Rock Band.
Everybody knows Guitar Hero, we all saw it on South Park, the experience...strumming on a fake guitar and playing a song, that's as far as it will ever get. They can add gold to the cymbals and real guitars to the drama, but it will stay the same, just a screen with some coloured notes that scroll down until you say otherwise.
Rock Band tries to put an end to the already ridiculous iterations of Guitar Hero by releasing this one game, with lots of downloadable content, which is all you will ever need, unless, of course, you're caught in the hate and drama of the internets and the seemingly unstoppable need to say "But it has no dragonforce".
Get this and expand, avoid buying and buying more and more, by buying less. Huh.