The margin for error in this business is very small.
Nintendo did some good things with the GameCube, and they did some bad things with the Wii, yet one has sold almost 4x more.
The main mistake with the GameCube IMO was it launched too late. Had it launched in fall 2000 with Zelda: Majora's Mask, Perfect Dark, and Conker's Bad Fur Day (they should've yanked these from the N64), I think it would've carved out a very nice no.2 spot for itself of 50-60 million+ sold in the end. It would've been a nice alternative to the PS2 which was hard to program for.
But they launched too late and let Microsoft get their act together and had to go toe to toe with Halo and got caught flat footed. And then it was very hard for them trying to fight off Sony and Microsoft.
Also yeah, the purple as the primary color and all that was a mistake. Should've been silver and black available for the Western launches, with the "wackier" colors being quietly rolled out later. They went to all the trouble to get Resident Evil exclusive and make games like Eternal Darkness and Metal Gear Solid: Twin Snakes -- there was no need to make the box look too Fisher Price-y. It was counter productive. Save the purple, etc. for the Game Boy.
Also I think DVD playback should've just been standard. Yes mini-DVDs were cute and loaded faster, but not having DVD playback killed Nintendo's price advantage, no one cared the GCN was $100 cheaper because the not playing DVDs kinda cancelled out the value proposition.
