Picture five or more players huddled around a Wii.
The number of people who can play is limited by the number of controllers that can connect. When that happens, you usually have the people who win or lose rotate out so that everyone gets a turn, right?
So be nice and give everybody a chance to play!
... ...That's how I feel anyway, but just in case you need a little help being nice (and since everyone has their own controller preferences), they went ahead and rigged up a Rotation mode.