because nintendo doesn't care if you beat, or even play the games, so long as you buy them. from a business point it's a terribly stupid idea, but as a person who loves playing games, I would definitely say it's a fun idea. I think we'll probably start to see online tournaments with various games (I'm hoping the next Wii Sports if there is one would allow for this) allowing you to win prizes. Or VC games. I know it's possible, Sega did it with Sega channel and that was many many many many many years ago. I think these are the games you'll see yourself getting something for free simply for having fun.
That said, including wii points, or exclusive software/minigames/VC downloads in the box with new games or new peripherals is not only a good idea, it's pretty much guaranteed. It may be combo deals, maybe not. Say EA sports releases Fight Night and NHL on the same day this year, or around the same time, register both and you get a free download of NHLPA 93 for sega genesis or some such thing... of course then people would scam it with free rentals, so they would have to subscribe to nintendo's unique pin code in the box method of distributing registration keys, and who knows if that'll go over or not. i bet you'll definitely see it with Nintendo produced games though.