I think hardcore game developers have given up on the Wii. The Wii is now for soccer moms and their little kids. I've always defended Nintendo against the notion that it is kiddy, but no longer. Gamers are no longer Nintendo's target audience.
I can understand why hardcore game developers would rather develop games for the 360/PS3/PC, but I do think we're going to start seeing some AAA hardcore games in the next year or two. Don't forget it takes 2 to 3 years to make a AAA hardcore game, and by 2007 and 2008 developers were realizing the Wii wasn't a fad.
As for Nintendo I'm sure they have plenty of hardcore games in development, they have just changed their marketing strategy so that they don't announce most games until a few months before they come out. Personally I think it's a bad idea and you don't build up hype among hardcore gamers, but I guess they think it's a good idea.