I can see many peoples' points in this debate, on both sides. I do believe that 3rd parties have a sort of "dip your toes into the water" approach to Wii gaming. Some have tried fairly ambitious titles and had their fingers burned, so to speak. I do believe though, if someone made a genuine AAA effort on the Wii with money spent, there would be decent returns. Would the sales match up to the HD consoles though? That is the million dollar question. Not one seems to be willing to take that risk. Sports games seem to do better on the Wii but the massive, cinematic type games, no one seems to really know. These sort of games would cost the Dev lots of money and there is definitely a risk of them crashing and burning on the Wii. Less so on the HD consoles. I do agree, that for the leading console, 3rd party support for the Wii is pretty lacklustre. However, looking at the highest selling SW on the Wii, all 3rd parties must see is a formidable barrier of Nintendo developed $$$$'s. This may make them reluctant to bring games out for the Wii, as they would fear Nintendo as a formidable competitor on the Wii. However, i do feel that some of these Devs, perhaps not those that have had their fingers burned, should at least have a decent go of bringing something genuinely AAA to the Wii. If not a blockbuster multiplat, then at least something with a decent amount of effort to at least implement some sort of intuitive and original, well thought out effort that actually makes good use of the interface on offer. Am sure some of the Publishers must look at the software charts, see the HUGE amounts of SW the Wii actually does sell; and it does! They must think to themselves "What can we do to get a slice of that?"
Well it's not that hard actually but it could involve a risk that they don't seem willing to take. We may never find out if a genuine blockbuster could be successful enough on the Wii. I'm sure most are "possible too. Saying they aren't is just a cop-out by the devs, trying their best to appease the audience they are alienating. Sure the games wouldn't look as good as on a HD console but if done properly and from the ground up, using the strengths of the console would be the way to go, anyway.
I honestly think it may depend on marketshare. Remember the Wii, in this respect is facing both HD consoles, as Devs seem to go EITHER the HD or Wii route. Whilst the Wii is at50% and it is widely accepted, then i can see some of the high-up suits at some of these companies demanding resources are shifted. If some of these Publishers/ Devs are in such a bad way financially as it has sometimes been reported and if this is indeed true, then i see it happening to an even greater extent. I will agknowledge there is a much smaller "hardcore userbase" on the Wii than on the HD consoles, although i do believe this base would follow wherever the games go. The introduction of both Sony's and MS's motion control could also have some impact of where future multilats go, too IMO.