Yeah exploited they were, but what if they would turn against their masters? as i said if Grom Hellscream one shoted Manoroth, immagine Fel Grom Hellscream.
I think the Legion risked a bit much when they enpowered orcs, even if they could control them.
They played with the Ultralisk as if they would play with a normal Zergling thats what they did.