Well . . . you're both right. They weren't crummy games, but they're not Wii games either -- not in the sense that you normally think of games for a new console. When you bought games for your Super NES, they were ALWAYS something that couldn't have been done on the NES. When you bought games for your Nintendo 64, they were ALWAYS something that couldn't be done on the Super NES. Same goes for Gamecube. But the Wii is different. The games you're talking about not only could be done on the Gamecube, but were actually made for the Gamecube and only artificially deemed Wii exclusives. Nobody wants to plunk down $$$ for a next-gen system for an experience that does not differ in any substantial way from the one they can get on their last-gen system.
I haven't played MP3 yet, but I suspect I would love it, and the Wii did bring something big to the table there, i.e., the best console fps controls in history.
But Nintendo has definitely left us hanging with a terrible drought of games. They released the system without a single full-on, deep gaming experience developed from the ground up to take advantage of the hardware (at least not one worth mentioning). The first we got was Wario Ware, which is literally a three-hour game from start to finish. Much later on we got Super Mario Strikers and, finally Metroid Prime, but that ain't very many games in a 9 month period.
And third parties were even worse. By far the best we got were Trauma Center and Resident Evil 4, both direct ports from inferior systems.