It's very simple, the gamecube and the Wii both have games centered around a group of people playing from the same unit. Mario Party, Super Smash Brothers, Mario Kart, Crystal Chronicles, and various other games all thrive in the party atmosphere. Party games also have a focus on luck over skill, which means they are usually fun for everyone although that doesn't necessarily mean they are easy or dull either. Wii Sports added to this, being a game adults could get into and play with little experience.
