I think I understand why there might be four switches, and it probably has nothing to do with them being needed, and everything to do with decreasing service calls.
4 Switches means that a single switch failure isn't going to take out the game.
Or, an alternate reason could be that it is just to make the pad more responsive, or that it exists so that the game can tell the difference between a foot barely rested on a pad and a mighty slam.
How are they wired, are all of them wired separately, or are all the ones for each switch wired together.