Third parties are in a bad spot right now with the wii. They see it as too risky to invest in a AAA title. They know that COD, Assasin's Creed, etc. are going to sell well for the HD systems, but they aren't sure if it will on the wii. They know that what it is needed in the wii is a "hardcore" AAA exclusive to finally get the audience they need to sell those games, but no one is willing to take that chance. Unlike Nintendo that makes money on harware, 3rd parties only have software revenue, so that is why they fear the risk. they go for the sure thing.
They test the current market to see if the "casuals" will buy into "hardcore" material but of course they don't. It's a different audience. The few stuff they sell is to the hardcore wii owners but those are not the larger part of the audience.
To answer the OP, they should not complaint, because they know what needs to be done. If for example GTA4 would have been a Wii exclusive, then a hardcore wii audience would have been expanded enough to sell more hardcore games in the future. (of course this is all opinion and speculation.
"¿Por qué justo a mí tenía que tocarme ser yo?"
