Gamecube to me is an odd console. It is certianly underrated and didn't deserve only 21 million sales IMO, but at the same time had sort of an image problem (weird purple lunchbox look, bizzare controller), and its library was nowhere near the PS2 in quality, and this is coming from a Nintendo fan. It also was hindered somewhat by its mostly gaming media branded "kiddie" image, much like the Wii with its "casual" image, which people were brainwashed into believing.
But still, it had some very good games, and some of which remain some of my favorites of all time. Metroid Prime, Donkey Konga, Eternal Darkess, RE4, Tales of Symphonia, Smash Bros Melee, etc. I think the main problem that killed the console is its image, from the weird appearence of the hardware itself, to the hit games that didn't really appeal to a mass audience and were primarily niche games. Also, I believe Sean Malstrom is on to something with his theory that the lack of a classic 2D Mario game really hindered it.
