There's no doubt it'll probably deter a few developers, but look at the DS. Quite a few games (e.g. Resident Evil) have been ported to it, and altered to make use of the DS' unique control system, so perhaps a similar situation could occur with the Wii.
I know what you mean. If you look at Madden 07, EA said that they would make a custom game for Wii which will utilize its features. I just hope that some of the more popular games won't be detered from using the wii because they aren't able to port their game properly.