Gamerace on 29 November 2012
Quite simply it's a matter of fun and accessibility. There are better games technically sure. But how many your mom could pick-up and play and have a great time with?
Mario Kart gives you a steering wheel and says Go! It's fun and anybody, no matter how badly they suck has a chance to win at least occasionally (or at least feel like they have a chance after 3 bullets...)
This on a system people bought for Wii Sports or Wii Fit.
