In the PC version, it made sense, because it was like you press 2 for pistol, 3 for shotgun, 4 for chaingun etc.
In the console versions, except the Jaguar, there are no 2, 3, 4, 5, 6, 7 buttons. So it's functionality is totally just for show.
But it would have been nice to show, in the XBLA version of Doom II, a mini d-pad in that area so the player might know which direction to press for certain weapons, instead of the 2 3 4 5 6 7 thing.
