Many consider MKWii's online to be a major component of the game. I don't see why this is any different especially since it is not required by the player to do so.
As far as the developers focus and what people actually do with the game see my earlier allusion to GTA.
Infinite lives and many checkpoints are a way of not punishing a user for being bad at the game. Something that limited life systems don't do.
At $199 the 360 has attained a mass market price point in America and Japan and will soon do so in Europe. (there are 3 versions of 360 and 2 of the PS3) The point in lowering thier price is to appeal to a larger market, and the same with upcoming titles(Lips, LBP etc.)
For that matter I suppose the PS2 was never a mass market console since it launched at $399. Or despite it's varied library of games (which is what both the PS3 and 360 are quite hastily working torwards).
