Take paladin, as an example: In a fight or flight rotation they need to do goring > royal > royal > goring into ogcd requiescat to maximise dps.
i'm not sure what game you are playing but paladin's job is to tank. And i can guarantee that a 360 potency attack from a paladin does significantly less than any attack from my bard. (ok just tested it for you, my 314 paladin vs my 316 bard, straight shot which is my filler did over 100 damage more than my paladin's royal authority despite only being a 100 potency attack. 2200 average straight shot, 2000-2100 average royal authority) that was also with fight or flight up from my paladin, and zero buffs up on my bard. Your arguement holds no water because despite having a higher potency the attack has significantly lower multipliers on the paladin.