let me explain, for Archer, AA would mess up their damage. using multi shot, trifurcate etc, the key is to stick multiple buffs on to one normal attack. if you have AA randomly going off, it messes up your buff stacking. if you make it not effect normal attacks, then the skill is kind of useless.
a archer generally goes,
multi shot multi shot raging ferocity blidside Basic attack Weaponskill1 weaponskill 2, trifurcate basic attack weaponskill. Its simply not an AA class really.
I know how they work, but you are putting in game design flaw into an unimplemented ranged auto attack to state your case.