Haha! Classic case of TGS rider not having a clue. If the bike is lighter it's easier to ride, you go bigger easier because you can move the bike round more easily and you tire far less quickly because it takes less effort to move it around! Obviously if you're a TGS rider, it'd be a f**king stupid thing to do, but if you're a smooth natty or comp rider, why not? There are only plus points, you don't need the bike to be strong, you need it to be light, so you'd be daft not to! Unless you regularly destroy rims that is.