Well a 6 axis position tracking device on the pc has traditionally cost upwards of 200 bucks on the pc. A wiimote is around 40.
Besides you forget, once nintendo makes a new controller it becomes the standard, period.
Dpad, invented by nintendo. Select and start buttons right on the controller... yep nintendo again. L and R buttons.. nintendo. Micro analog stick.... nintendo. Rumble pack, nintendo. Save card right on the controller... nintendo. 4 ports built into the system... the 4 button layout (as opposed to previous attempts which had a single long line of 3 or more buttons). I could go on, but the point is nintendo has been silently deciding the future of home consoles since the beginning, it's just nobody has noticed until now.
So within a few years all games will use positioning technology, even on the pc. The wiimote could be used as a controller for fps right now on the pc if a proper driver could be written. Not to mention light guns, which the controller basically is. Also steering wheels, flight sticks ect....