The Alliance attacking Lordaeron first would have been grim and morally gray, but still justified in that some could say it was a response to the Gathering and paranoia in the Alliance with Sylvanas as warchief. Rather than the Horde looking like a wild animal blindly attacking the Alliance simply out of fear, the Alliance would have been attacking a Horde under a Warchief they’d have reasonable suspicion of. If the Alliance was the one to bomb Lordaeron upon realizing they couldn’t keep it, that would have been brutal, but then…
…Teldrassil and the War of Thorns the following week. Sylvanas burns Teldrassil in vengeance, and both sides are justifiably angry and vengeful in a way which frames the Horde as aggrieved and vicious, and the Alliance as intelligent and well-armed but more close-minded. Far more balanced. God, what a simple little timeline shift could have solved…