Actually your wrong and right.
They can make crap and it will be bought. Because the average Wii owner or buyer is a casual gamer. Infact its said that the average Wii owner doesnt know wtf Super Mario Galaxy is. So yes, they can make trash and the Wii owners will buy it, and yes they can make good games yet there's a good chance it will not sell. Wii does not sell 3rd party games well. So I think thats the main reason why developers still doubt the Wii. If its not a Nintendo game, chances are it wont sell well unless its a very known title like Resident Evil. Look at Zack and Wiki, good game but sold bad. This is going to make Capcom more reluctant to make Wii titles. Maybe thats why they wont make a cut down version of RE5? I don't know.
Its like some guy at Game Trailer said. A smart company will not spend 2 years creating a great game for the Wii if they can make a crappy mini-game fest for 3 months and get the same sales figures. You can only really blame yourselves if you buy these shit games because it makes it seem like Wii owners are nothing but a bunch of casual mini game lovers. Which in some sense is true if you notice people in these forums seem to like games like that.
So if I were a developer and I thought "Hmm, I love great games with depth, story, and gameplay. So ill make it on the Wii for those hardcore gamers like me" "No wait... It takes too long and we don't get enough of a profit from the Wii's casual community" "Lets just spend 3 months on a pack of mini-games to raise money to make a great game on the PS3 and Xbox which WILL bring us sales numbers"
You have to think like a developer that needs to eat. They need money, they can't spend 2 years on a game and get hardly any profit, its just not worth it.