Mario Kart Wii: Undeserving sales

[MDMAlliance]

There are quite a handful of other games like this. Why complain about Mario Kart? We have Halo, Call of Duty, Diablo, Resident Evil, etc. (At least the main series titles for RE)
They may not sell over 30m like Mario Kart did, but I think it's kind of obvious why it sold so many.