The third-party development situation for the Wii seems to be a catch-22 scenario.
As long as third-party software continues to sell poorly when compared to first- and second-party software, third parties will not make an honest effort with a first-string development team, and will fail to produce outstanding titles for the Wii.
As long as third-party developers continue to produce shovelware, their software will continue to sell poorly when compared to first- and second-party software.
A game like the Wii version of Spiderman 3 should never have been released in that condition. But the publisher said "go ahead, release it, those casual gamers will buy anything that says "spiderman" on it while the movie is still in theaters" when they should've said "this is CRAP, fix it up, get it looking better and playing better." They got exactly what they deserved, pathetic sales even compared to the PS3 game with a much smaller userbase.
Unfortunately, I fear this will be taken as a sign that Wii owners are only interested in Nintendo's games, rather than a sign that Wii owners are, like most gamers, only interested in GOOD games.