Originally Posted by
Destinas
So, spoilers.
We're fighting the Jailer, who is apparently an ancient being in charge of the Maw, where the worst of the worst souls go. He and his allies (Sylvanas, Mueh'zala, others) have broken how the Shadowlands work, sending all souls to the Maw instead of other places.
This is bad because if the other zones do not get souls/anima, things break in the Shadowlands and even in reality. If Ardenweald cannot get anima, the spirits of Wild Gods cannot be reborn. If Maldraxxus cannot get anima, they cannot create an army to protect the Shadowlands from the armies of the Light and Void. Kyrians would not be able to ferry souls to their deserved afterlives. The Venthyr would not be able to redeem souls in Revendreth. And, we will likely see other places in patches. We already see Bwonsamdi's realm as a dungeon, not to mention Oribos.
Likewise, we care about these four zones because their leaders are apparently ancient beings that are part of some sort of "Pantheon of Death" - some oppose the Jailer, some may have sided with him. There are many infinite places, but these seem to be four of the more important ones.
The veil between reality and death is also broken, allowing undead and souls to attack Azeroth as well from the Maw. If the Jailer is strong enough from anima, it's possible he could harm reality even further, killing everyone and making their afterlives an unending torture. No one would be sent to any kind of heaven when they die.
So it's probably the biggest threat we've ever faced in WoW. Sure, we fought undead and necromancers before, but they were borrowing powers from the Shadowlands. Sure, we've fought cosmic powers, but the Jailer is apparently more ancient and powerful than even the Titans.
In the end, though, it seems that Blizzard will be focusing more on greater cosmic powers in the future. At least, that's their mission statement when they announced Shadowlands last year. Apparently the Jailer is the beginning of them exploring WoW's cosmology. So, I wouldn't expect more simple stories going forward.