Is the Wii gaming? I would say it more or less depends on the game and the player. A person who plays WiiFit just to try and get fit, no, that's not gaming. That's trying to get fit in your own home, an exercise tape with more personalization and interactivity.
A person who plays WiiFit to try and "get the best score." (I honestly don't know how it works, but a one-upmanship wouldn't be that hard to do with anything) Well...a bit harder, so I'd say yes and no. It's not in the sense of that WiiFit isn't meant to be a game anymore than a plush dog is meant to be a sub for a real one. But then, yes, it is, because the person playing has turned it into a game between himself and whoever else is playing.
A person who plays something like No More Heroes? Yes, and yes. That is a game and if they are playing it, they are playing it to game. No question.
So...the short of my long post is my second sentence: It more or less depends on the player and the game. In my opinion, of course.