Anyone who walked into a Human Computer Interaction lab between 1998 and 2002 would have been able to tell you that many people have been working on gyroscopic mice and direct screen pointing devices as replacements for conventional mice for a very long time.
What makes Nintendo unique is that they realized the potential for both of these devices, packaged them in such a way that they could work in both conventional games (Wiimote+nunchuck) as well as in new games (wiimote), and made these devices the standard input device on a major platform to force developers to use them.
Products like the eyetoy and other unconventional input devices could have been just as successful but developers will never take much advantage of them because the potential reward is so small ...
