Most of the worries that people have are really not going to be an issue in the future. Just cause Brain Training and Nintendogs sold over 4 million doesn't mean that every game on the DS is a non-game. And interestingly enough, the best selling game in Japan on DS isn't Nintendogs or BT, but rather New Super Mario Bros.
I just don't see the problem when PS2 had its Eyetoy sell like 7 million units, people ever talking about Sony killing gaming. I'm sure a bunch of developers tried to imitate Eyetoy games on PS2, but it didn't cause hardcore games to stop coming. Tetris must be one of the easiest games to make, but that didn't kill the industry did it? The crux of this issue is that the millions of people who buy Mario's, Zeldas, Halos, Metal Gears, Final Fantasies, etc. aren't going to just magically transform into non-gamers.
Just saying if you're going to hate on Nintendo, at least hate on them for legitimate reasons, like making weak ass hardware that'll probably have an affect on competitor's hardware in the future.