It makes since. Nintendo started by making games for kids. Then, they moved onto RPGs and other games considered more for adults. Then the GameCube focused on multiplayer and party games with class. Now we have workout sessions and the ability to check our blood pressure and weight.
Seriously, I don't understand how people can say things like the OP. Nintendo makes excercise equipment for retirement homes. It is really nice to see a company make new devices for senior crowds, but it's not a true video game console. Sure, it may have a few really good games, but I don't remember doing yoga and checking my pulse to save the princess on the NES.
The Wii is an impressive piece of technology from Nintendo. They didn't make it for us, though. Some people might still enjoy it. It does have some very fun games. But saying Nintendo is going to take Sony and Microsoft out is like saying insulin will replace food.