Let's make a clear distinction between a "war-hungry character" like MoP-Legion Jaina or WotLK Varian and a "crazy psycho lunatic bitch character" like Garrosh and Sylvanas.
What we Alliance players wanted was the former. Someone who has a spine and will not tolerate any transgression commited against the Alliance. But also someone who is not generic pure evil.
That's why many people complained how Jaina went from "beware... of me!" in BfA pre-patch, to being horny for Thrall in 8.2.
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You are comparing an Aspect empowered by the Titans and by the Old God N'Zoth, to a faction of barbarians living in mud huts. Scientifically, your comparison doesn't make sense. What Deathwing can do is irrelevant to what the Horde can do.
Also, last I checked, we only breached Antorus thanks to the Vindicaar. Which is used by the Alliance, btw. Since the Horde are barbarians living in mud huts who couldn't possibly know how to build a spaceship.