im guessing that's in case they wanted to add to the controller's design, much like the way they had few extra places to add wires on the psx controller, which they used to add force feedback, analog sticks, and analog buttonsAntoineWG wrote:The SNES connector is somewhat deceptive. There are only 5 wires in the controller cable. I'm not sure if the other 2 are even connected inside the system.
and im almost certain that the other 2 are connected inside the snes, because otherwise there wouldnt be any room for extension. also, extension cords usually (if not always) have all 7 wires in case a controller makes use of some weird ones.
they're also sometimes used for other types of controllers like guns, driving wheels and the such