It wouldn't matter. Even if the next Mario Kart didn't allow you to reset your saves what are you really losing. Stuck with the best times and all gold cups? Something like that really doesn't matter. It's the same with Resident Evil Mercenaries and people are blowing it out of proportion.
Some of the legitimate reviews are based on the fact that the game is a bare bones mini game, not about the save file problem.
There are other reviews by people who don't own the game and have no idea what they're talking about, just heard that you have a single save file. Here's just one of the many fine examples.
http://www.amazon.com/review/RUFFLRU...tag=&linkCode=
A review is supposed to be what you've played and your opinions on a game. Not to bash a game while not even being close to what problems that are contained within the game.