Not everyone like rock music, like non-gamers
Are you suggesting that non-gamers don't like rock music. I would seriously beg to differ. I figure that is easily the most universal genre of music to go with. If it was all current stuff then yeah, it would be limited, but with a good mix of new stuff and classics it has very universal appeal with people of all ages. Okay maybe really old geezers don't like rock music but compared to classical music it's no contest. I like classical music a fair bit but it's niche. It's inoffensive in that everyone CAN like it or at least tolerate it. But kids and teenagers wouldn't be interested and I think most people if given the choice between rock or classical would pick rock. Classical music is somewhat elitist. It's of a high culture ie: not mainstream, not casual, not non-gamer. Nintendo typically thinks that being non-offensive is the same as having mass appeal but it isn't. That's why they're so often associated as being for kids.
Actually, haven't there been rumblings that Wii Play is more about "jamming" than rhythm gaming?
That's pretty cool. Well I think it is as a musician. Though I worry that Nintendo shys a little too much from the competitive nature of games. A "jamming" game sounds so them. Guitar Hero is a challenge and you can like suck and lose. The game requires you to be good at it. Nintendo's attitude with non-games is a little more politically correct. Like having goals and objectives that can be won or lost make people feel bad about themselves. It's the "everyone's special" routine. I think Nintendo could make a good rhythm game but focusing on jamming is sort of a cop out. It's funny that they really challenged videogames by making incredibly safe games. They shouldn't be so afraid of scaring the casuals.
Rock Band attracts the same audience but does so in a way that's actually cool, you know? Wii Sports and Wii Fit in comparison are the videogame equivalent of easy listening. Nintendo is popular but they sure as hell ain't cool.