Simple, snaking is a cheat, ive proven a lot of times snaking is not needed to win, at least on mario kart wii, IF you select the correct tracks. But nintendo made a big mistake making this move possible, now they tried to take it out but since gamers just got too used to snaking, nintendo feared if they take out snaking many gamers wont buy their games. Thats the only reason snaking is still in it.
As for being a legal cheat, well snaking was done by nintendo on porpuse, its not a bug, but gamers just exploited the move to the point its a cheat and unfair to real players that know how to play the game. Knowing how to make a move doesnt make you a master in a game...