There is a major difference between the Lich King's Scourge and Sylvanas' Forsaken; Scourge had no free will, period. Forsaken are generally free to do whatever after being raised (see Putress). It's only because of gameplay reasons that player Forsaken all join the Horde. Others either choose to return to death, join the Argent Crusade or independence (however long that lasts).
Goal-wise she isn't the same as Garrosh either. Only "antagonizing" force she has on her borders anymore is the Argent Crusade in the Plaguelands and they're neutral. Can't think of any territory expansion she did of her own volition other than South Shore which was a perfectly viable military target. The use of the plague is the only questionable act about South Shore that comes to mind.
I never said she was the same as the Lich King only she is raising an army the same way (killing humans to increase her army). The forsaken used to be about free will but now she is killing people against their will with the sole ambition to claim as much land for herself and her race. She is literally doing what Vol'jin despised so much about Garrosh.