This is something I've been thinking about quite a bit lately, the balance between the scale of the threats we face in WoW and the expansions/patches they come in. Nobody else has seemed to really address it, so here I go:
-The first three expansions were fine, this issue wasn't really there.
-MoP is where this first starts to be a problem in my opinion. We get an entire expansion of Pandaria and Pandarens. Such a tiny, tiny part of Warcraft as a whole gets dragged out for a whole 2-year expansion. Tiny threat, evil Garrosh powered by Sha.
-WoD, an entire expansion of going to an *alternate*, past version of *another planet* which we already explored in modern day. We don't go into our own past, we don't visit another interesting planet in the functionally infinite Warcraft universe, we go into Outland's past...for another 2 years.
-Legion went way, way, way too far in the other direction in my opinion. We get: The Third Invasion of the Legion, The Broken Isles, The Emerald Nightmare, Argus, The Return Of The Titans, and the defeat of the biggest bad in all of Warcraft (up until they retconned Void Lords into existence)...all in one expansion. Blizzard blew all their lore cooldowns here. And the result in my opinion was fun...but really rushed and forced.
-BFA kinda seemed alright to me so far. We get faction warfare, Kul'Tiras, Zandalar, and some light Naga and Old God stuff. Lots of good stuff, but not the frankly psychotic light-speed pace of Legion.
-Until now, where it is starting to seem like they are pulling a Legion again. 8.2 is going to Nazjatar and defeating the leader of the naga. It looks like 8.3 is gonna be us banding together to defeat N'Zoth, dropping the faction war entirely. If this is the case, 8.2 and 8.3 are going to have content more worthy of being full expansions than Draenor or Pandaria.
-Then what's left? A WotLk re-hash with Bolvar and/or Sylvanas? Going into the void and somehow fighting the Void Lords, leaving nothing left in the whole warcraft universe? I feel like there is a struggle within Blizzard between people wanting to do cool, big, cosmic threats and people wanting to scale it back to just being random nobodies killing boars all day.