Update: I was unfortunately not aware of Shamus Young's severe criticism of Fallout 3 available here to link in the original piece and I regret that. It dovetails rather nicely with what I've written and it's much better executed than my piece. I strongly recommend anyone...
Director's Cuts, How To guides, Rocksmiths... the world of downloads are full of things you'd never consider a game.... Wait a second... what the hell is an Enslaved? Eh, screw it, let's just play Beer Pong!
If you do your spring cleaning in winter, guess what you don't have to do come Spring? Nintendo is using the same idealogy to obtain faster than normal rates of selling-all-the-downloads.