Your first point: install base doesn't mean good sales. This is true and you provided us some decent examples.
Just below the surface: developers may be better off going with a system with a smaller install base. Possibly true, but you did not give us any example of where this was the case. Your examples could have sold better or worse on a different platform.
Just below that (and the point I think you really wanted to make): developers are not going to develop for the Wii just because it will have 50%+ market share. Of course they are not, you may rest at ease. But, more games will take advantage of the huge Wii userbase that is pretty anxious to spend money.
"You can never jump away from Conclusions. Getting back is not so easy. That's why we're so terribly crowded here."
Canby - The Phantom Tollbooth
