I figure it does give them free will back, but a good chunk of the Scourge is fairly mindless (Abonimations, Ghouls, Zombies, etc.) they would just go off on one big Thanksgiving style food binge, infecting what corpses they do chow down on and spread the plague.

Furthermore, various Scourge leaders along with the Banshee Queen would probably spark various civil wars for undead dominance that would get quite a few innocents swept up in the cross fires. I mean, Arthas already does a fair amount of sweeping innocents up into it all, but looking at the current Scourge leadership, most come off as hesitant to act due to fear of pissing off the Lich King should they fail. Furthermore, the entire Cult of the Damn comes off as totally screwed over by stupid schemes and bureaucracy. It's like their the only ones to try and act on their own plans because they are too feverishly in love with the Lich King and thus even him utterly destroying them seems to be A-OK with them since it is a form of death. For them, as the Spider Lady in Naxx put it, the greatest blessing is to die in the master's name. Free to fail and run away and try again and without having to deal with the Cult's idiocy, who knows what actual damage various leaders in the Scourge structure could deal.

I'll agree, it isn't much to go on, but that's my 2 cents. Overall, I'm a bit disappointed with Blizzard in dealing with Scourge lore in Wrath so far. Am I the only one that remembers the Obsidian Statues and such in W3: Frozen Throne and often wonder now that we are in Northrend where Gargoyles come from? I mean, supposedly they were originally Northrend beasts as described back in WC3. I find it a bit odd we don't see any nests of a few feral ones or at least their dwellings/construction area.