Naruto, I am not saying that there are no hardcore Wii games. What I am saying is that the few games that we do have (and you can take Overkill and Word at War off the list because they are not new IP's) have not sold nearly well enough compared to similar games on the HD consoles.
I know there are good mature games on Wii, believe me. I also know that there are exponentially more of those games on the HD consoles AND they have good sales. Which causes a chain reaction to make more developers design games for HD instead of Wii. Which is why games like Infamous and Prototype are not on the Wii.
# of games above 75 on Metacritic (including downloadable):
360: 241 DS: 144
PS3: 152 PSP: 126
Wii: 85