Not sure what kind of games it is, but 3rd parties are making plenty of money on Wii, just not in the Top 20 where they can brag about it.
That may be part of their problem with not advertising, as most Wii games that sell, do it under the radar. I'm sure plenty of those games were not full priced and many were probably bargain bin, but they were still selling.
According to some other chart I saw, 3rd parties are selling more software on the Wii than on the 360, and their money situation could be improved if they just upped the profile of the games they are releasing on the Wii. We don't need Assassins Creed 1 & 2, but it would be nice to atleast get a game of similar effort and scale.