People buy their consoles to game mostly, and game in a certain way... with a standard controller.
Microsoft tried to do way to much with XBOX... all that is secondary to gaming, and are nice afterthoughts, but no one wants to pay for them, because they didn't ask for it in the first place.
Nintendo's gimmicks make me scratch my head... Their handheld market is so strong because its the closest their fans can get to normal gaming with classic buttons. You think they'd have learned by now after Power Pad, Zapper, Superscope 6, Power Glove, R.O.B., Wii Mote, Wii U game pad.... the list goes on.
Sony def doesn't need to be the only console on the market, it will just cause a PS3 era type blunder with no competition to make them change. In a fantasy world Nintendo would make Gamecube 2 and actually put hardware that was next gen in it.