It's harsh, and I've been trying to come up with a word for this so the impact isn't as severe (and it can apply to other topics as well), but the whole thing is very similar to the illegal immigration debate. Hispanics aren't entering America so they can transform it into Mexico 2; that just happens to be an unsettlingly possible side-effect of a bunch of people simultaneuously wanting the same thing. Same with "causals"; it's not like they're all going, "oh, man, I can't wait until all everything's Wii Fit and Brain Age! I'm going to intentionally get everyone I know to start playing simple, cheap games! That'll show those 'hardcore gamers!'". They just want to have fun, but that unfortunately has the side-effect of transforming Nintendo (and, slowly, the rest of the gaming industry) into what it is now. It's not them--it's me.
Also, it is not an opinion, but a solid fact that everybody who saw the E3 Nintendo conference was let down. A fact. The minute you drive to E3 to watch it live or get on G4/1UP.com to see a feed, you're pretty much officially a gamer. Not a "casual". A gamer. Like us. And, if so, you probably aren't incredibly psyched for frisbee-throwing in Wii Sports Resort or exuberant flute-playing in a field of flowers in Wii Music. Which makes the whole thing a million times more idiotic, because what was the point of having Cammie Dunway (or whatever that ditz's name was--anyone who reminds me of my second-grade teacher should not be in charge of trying to make me like videogames) talk about huge smiles and snowboarding accidents to people's moms if everybody watching the god-dang thing obviously was not even into that stuff!? And then, as in the link I posted above, Miyamoto says E3 shouldn't be for showing "core" games. Double-you-tee-eff.
I've been considering starting some sort of blog-type thing at some point about me owning only a Wii. At this point, I've decided it might be fun, in a sadistic, documentary-style way (like Supersize Me or one of those Japanese reality TV shows), to chronicle the life of a gamer trying to survive with nothing but a Wii (and a DS).