Why isn't samus in a mario kart game?

[SmokedHostage]

I'm glad Samus isn't in Mario Kart Wii, If Samus were to ever be in a racing game it should be "Metroid Kart" or "F-Zero Wii" as a cameo. Donkey Kong and Diddy Kong are in MKWii because they stem from Donkey Kong.