When the computer cheats. If I happen to get half-a-lap ahead of the computer racers on Mario Kart, they should not all-of-a-sudden be right on my tail.
This is annoying against the computer, yes. The Wii Mario-Kart is FINALLY going to add this option for multi-player, though, which is a GOOD thing.
I'll finally be able to play with various friends or family members without lapping them. When I play the computer I want to win, but when I'm playing with my friends I want it to stay competitive or they don't want to play again.
This has always been backwards. They're finally adding it where it makes sense.