Well, there’s two, the first being that no expansion tells a complete story anymore, but I won’t touch on that.
The other is that WoW has moved on from being a story and is becoming a mythology. The main reason why everyone is so disenfranchised with the story is that it has become too crazy and unrelatable. Take Arthas - you can relate to him. His story is a classic - a man of great expectation becoming corrupted in pursuit of his ideals. Not only can you relate to it, but chances are you know someone in your life who is the real life embodiment of this. So his story is relatable.
But now… the story is about the mingling of Titans, and how systems work in a fictional world and none of it is relatable. Yes, it makes sense internally for the most part, but it is impossible for anyone as a consumer to insert themselves into the story.
With mythology, 90% of the burden is carried by the fact that gods’ mingling affects our world. Our reality. But now we’re being asked to invest ourselves into a mythology and grand narrative that has nothing to do with our own existence.
Stories take too long to tell, by the time you reach the end, you’ve forgotten the beginning, you’ve forgotten what the story’s idea is. No expansion’s story should bleed into the next one, or should be told in books.
A HUGE reason why BFA’s story was so disappointing is that there was no actual end to the expansion. Yes, we killed an Old Squid, who didn’t really make an appearance through the entirety of this expansion’s run. N’zoth is dead… allegedly, but who cares? The interesting part was the war between the horde and alliance, and Sylvanas’ pursuit and none of those got satisfying endings.
Hell… even the cannon in Azshara didn’t get fired. Bigger isn’t always better. Especially in WoW’s story structure. It is actually hard to go and play the whole story, from Legion through BFA to Shadowlands, because so much of it happens in raids. This is another reason why Blizz should contain all stories to one expansion.
The worst part is that we can already start predicting what 10.0 will be, because its story is already being set up. And it’s sad, because you can again make the assumption that 9.0 will be an incomplete story.
Each expansion is basically its own game, and each expansion must offer a complete story that ends with a satisfying ending. It doesn’t matter how well the intrigue has been weaved in since cataclysm, and how we find Shadowlands references in Mists of Pandaria… if there’s no satisfying end to each episode of the story.
This is the problem. Blizz is obsessed with telling a never-ending story that keeps you edging all of the time, but it never gives you this satisfactory release. You never get the feeling of killing Illidan in the Black Temple, or Arthas in Icecrown. Hell, even Deathwing felt like an ending to a story. This is why people don’t like it.