Nintendo published most of those games thus made most of the money. How does that prove anything except that Nintendo IPs sell well on Nintendo hardware? That doesn't assure 3rd parties that their own games will perform well. Nintendo didn't give anyone a reason to believe GCN was a better choice than PS2. It just was and that was that.
When Sony took the market by storm, Nintendo let them take it... by making dipsh*t decisions. It's kind of what Sony is doing now. Of course, Gamecube support in general could have been better. The thing is that there was no real reason to choose GCN over PS2. Then, Nintendo did almost everything to make the most unappealing console ever, learning surprisingly little from N64. I don't blame Konami, or any 3rd party publisher, at all shafting Gamecube. It was easier to make money on PS2. Perhaps they could release the same game on GCN and sell just as much, but why? Why not just release it on Playstation 2? And at least you sell with the potential that maybe you'll sell more due to a higher user base.
Nintendo used to say that they weren't competing with Sony and Microsoft, but their system did the same thing as the other consoles did... sometimes worse. With Wii, they're actually doing something different. Now they have something to entice developers with; they have multiple reasons why publishers should support them and more importantly, why publishers should support them over Sony and Microsoft. Plus, it doesn't hurt that Wii is selling like crazy. Nintendo has still made mistakes... but they've made fewer mistakes than their competitors, just as Sony has made fewer mistakes than competitors in the previous 2 generations.