I don't like the idea of giving any team home field advantage for no reason. If the Jets/Giants get in, they WILL have more fans. If the Patriots get in, they will have more enemies. If it snows, southern teams who aren't used to dealing with snow have a severe disadvantage that other southern teams haven't had in the superbowl lately. If weather makes it a bad game(ie a scoreless snow game), how much will that hurt the ratings?
Hell, if we're just going to award the superbowl to a non-neutral place, why not just give the team with the better record home-field advantage?