Mario in space - Why not?
The only interest I have in the 360 is for Dead Rising. The only interest I have in a PS3 is... well, I don't have any interest in it.
The Wii offers me something different, a new way of playing games and a refreshing new control style.
BTW - You can officially consider me a "mainstream casual gamer" now, as well. I barely have any time for this shit and when I do I usually tire of whatever I'm playing after about an hour or so. I think everyone shitting on the new "crazy style" for the Wii is failing to realize that gaming has become tiring, cumbersome and just plain old boring. I'll take Trauma Centre: Second Opinion over GTA4 or Metal Gear or Final Fantasy VII Part 1212343143.6 any day of the week.
In other words: I'll be buying a Wii, for sure, when it launches.