Gamecube has the simplicty factor to it.  If a bunch of friends want to play a multiplayer game, they don't need that 5 hours learning curve to get good at the game.  Thats why those Mario Karts, Smash Brothers, Mario Parties make the best multiplayer games.
I just think ALOT of games on PS2 and XBox are too complex these days.  I don't want to spend an entire evening at a friends house to learn the game while getting betten up by a buddy.
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Infants Wellbutrin