Nope that is not it at all... OK, maybe the game is stolen, but that is a rare scenerio. See, the carts are sold to regions... you are not supposed to operator or sell the carts outside of your region... removing the serial... hmm, where was this cart supposed to be from... see the point! Not that SNK cares, but companies do it to cover their ass so when a Japanese Puzzle Bobble shows up in an American Arcade, no one gets fines out the booty. That is the real reason,
-Nick