we have a 4 player panel right here at work, where player 3 and 4 are at 45degree angles, and just played some sunset riders, TMNT, gauntlet, and crime fighters, taking turns between player 3 and 4, and i cannot imagine trying to play them if the sticks were not rotated 45 degrees. in my mind, up is away from me, not up on the screen, right it towards the buttons.. no matter what angle i am playing at, the joystick needs to be relative to my body, not the screen. it does limit your ability to play dual joystick games, but for 4 player games, i can't imagine it any other way. if i were playing with other people and the joysticks weren't rotated, i'd have to be standing along the front edge of the panel, and not at an angle like the buttons are
just because people tell you it needs to be one way, doesnt make that true...your best bet is to make a mock panel and test it.