I mean, Thrall set up the Orcs in a desert, as a way of reminding them of their former evil. But many, if not all Orcs are ungrateful, with some even seeing Thrall as a bad leader (Garrosh). If they don't want to live in a desert, and don't want to repent, then they need to get off Azeroth and go right back to Draenor. Regardless of it's condition, it's another, far better way of reminding the Orcs of their sins, while being much more resourceful. They won't have to savagely kill or enslave other races, or do any of the evil deeds Garrosh is ordering around for now, to a large extent. Hell, Garrosh doesn't even have to die! If he leads like he does now, on Draenor, it wouldn't be that negative.