There's plenty of room to play Forsaken without being SO EVIL that it makes it grating to the rest of the Horde, if Blizz would bother to make the Forsaken SMARTER about hiding it, or who they target.
Instead of vivisecting ALLIANCE forces (y'know, the one global political-alliance-superpower that poses a threat to the horde) put bandits on the table, or criminals that you buy from Alliance nobles, or evil cultists that work for the scourge or legion or whatever...
Instead of sewing a bunch of orcs into abominations without their permission, get a bunch of orc volunteers to try alchemic treatments that turn em into Dire Orcs, temporarily or otherwise.
Instead of poisoning land so that only you can live in it (which alienates your allies) create ways to collect the poison/corruption from land that you clean up and run off with it. Belfs and others would LITERALLY BE PAYING FORSAKEN to gather useful research material, it's a win win!