Someone has it in perspective
Given that the Game Cube had a lower price than the PS2 or XBox and there are still some 600 games on the system (give or take), you can't convince me it is disappointing. Disappointing would have been closer to 100-150 games, a $250-299 price tag and a 2 year shelf life. Bottom line. Given the long period of time that the Game Cube was $99-149, which is STILL less expensive than the PSP, what is there to gripe about given the GC's game library?
Couple that with the fact that people KNEW going in (or should have known) that there would be a lot of first party games and some stuff for a younger audience, you'd have to say the Game Cube lived up to expectations. Did anyone really expect a whole lot more than they ended up getting?
In General:
Nintendo may have promised the moon before the GC came out but every company says that about their console. No one goes into a console launch saying they'll be in third place and will have long stretches without AAA games. Atari or Sega never did that. Would it have been more honest or smarter for Nintendo to come out and say before the launch that some third parties would mostly ignore the Cube or that some of the top games could be found on PS2 or XBox anyway? They did the usual drill of selling the system and creating hype, same as Sega did with the Saturn and Dreamcast. Sony and Microsoft probably have an unfulfilled promise or two that I'm sure someone could dig up.
So people who had more reasonable expectations are the ones less likely to call the Game Cube disappointing. People who actually believed Nintendo's lip service, which is no different than any other company, are the most bitter.