“Cosmic war is brewing” - they said.
Azeroth is not a world soul, it is a cog in Machine of Death, that much has been revealed in SL, with Azeroth firmly sit in the center of chamber in which we fought Jailer. But Zovaal did not tried to “conquer” Azeroth, instead he tried destroy it Why? Because - “Death has never meant to be chained”, by his own words. Supporting this (tho, it might be coincidence) the Naary which we saved in Revedreath, said “Death must know it place”, clearly indicating the possibility of Death “spilling out” into living words, or Death “overstepping” it boundaries. Which mean that in global scheme of things, Azeroth’s function inside of Machine of Death, - might be “containment” or “gatekeeping” Death.
If so, then why does every force in WoW universe tries to take control over Azeroth? Not destroy it!, - but “convert” to it own image?! Perhaps Azeroth is gateway to Death realms, which supposed to open up at certain point (as mentioned above). Lets say in event when cosmic forces start to tear up the universe apart, - the gate of Death open up, legions of Death empowered by anima (which now can exist outside Death realms) shallow everything (99 level Kael empowered by torghast one-shoting pantheon of chaos/void), after which universe will be remade anew. It might be the true, because it would make sense of to why cosmic forces is trying to take control over Azeroth, but not destroy it.
Emerald dream - what is it? In current lore, it has been established that it hasn’t been created by titans, they only enslaved/controlled it. Which might mean that the first cosmic force to invade Azeroth was - Life. It infested Azeroth with “emerald dream” corrupting the undead guardians of Azeroth into become living organisms. Because it makes sense for an element of Machine of Death to be guarded by undeads, and as we now know, the Aspect fought against first undeads.
Then it was void. Not sure how, but guess what - we all know that void HATES undeads? Now we might know why? Undeads safeguarded Azeroth against Life/Void. And void just as Life, fears opening gates of Death.
Then we have Titans, whos stupidly assumed that Azeroth is one of them. After titans, we got burning crusade lead by proxy of Jailer - Sargeras who has created the Unmaker and then stab the Azeroth.
Now with primalists, i guess we will finally have the planet directly defend itself against all invaders.
TL;DR: Jailer tried to destroy Azeroth, to open the gates of Death and bring universe to it knees. Other forces trying to control it, so Legions of Death would not put every other force into drunk tank for trashing the place, in case of all out cosmic war.