Well, the other potential is that the Mario Kart Arcade games are unlocked when you beat Mario Kart Wii...or their tracks are included in the game from the beginning.
I don't mind Pacman and Ghost being in Mario Kart. Its a racing game...who you race isn't as important as how the game races and feels.
I have all been for Mario Kart going the direction of a Nintendo Kart game, but I know I am in the complete minority in that, and I actually understand why. Just to me it isn't a big deal.