I used to be a Nintendo U64 developer (mostly game AI, a bit of graphics). The U64 was a good platform, but I stand by my statement: the Wii is awesome because the games are *fun*.
BTW, even the Wii Fit "games" are cool: Yoga, balance exercises, etc. Lots of fun, and it is a good break during the day (I work at home as a software developer and author). I live 150 feet from a National Park trail head, but going on a hike takes hours, and the Wii games provide some fun and gets me away from my laptop - good for 10 minute breaks.
On the other hand, some of the games I have seen on (for example) the XBox are fairly much psychotic. What kind of people like to play games here they shoot people. If I want to shoot a gun I go my local the shooting range (I only shoot aluminum cans that don't have mothers :-)
Seriously, I don't intend to insult anyone, but I look at some of the violent video games and it makes me think of the fall of western civilization.