So what exactly are the consequences then? When Garrosh used it, there were literally zero negative consequences to him. Hell, there's even a "cavern of time" with a bloody tour guide. There's just this rhetoric that history shouldn't be changed but it's not explained why and even if there are consequences, they most certainly aren't world ending so I don't think most factions would care.. especially if it would help to stop a world ending threat.
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Death is more like alternate life though. In WoW lore there is literally no difference between the living and the dead. The dead can heal, eat food, even lay eggs.. have babies? They just turn emo and start liking dark colors and stuff.
I'd say the only reason the Void doesn't like them is that the process of dying and turning into undead makes them immune to Voids greatest weapon.. those mind shenanigans, visions, madness, whispers etc.