Using RT to fire and LT to aim is wrong for infantry too- they're both analogue inputs while fire and aim are digital actions that could be used on the bumpers freeing up the triggers for leaning which is analogue, in fact aim doesn't work properly on the trigger either it just gives you zoom on the cross hairs.
re-mapping is a colossal pain in the poop-chute cos you have to do everything from scratch.
I honestly can't see any valid reason to have the triggers as fire and aim when the bumpers are right there to do he job better.