Nintendo doesn't make throwaway games.

[Nintendogamer]

Also games like mario kart wii will make you want to play it again, imagine you only had one more gold cup to win on 150 CC, but you are kind of scared to do so because of blue shells and the such will stop you but you will always give it a go untill you win that cup, and there's the odd time you want to go back and play with a different character :D