It's bad writing, for sure. Danuser and whoever helps come up with the big story lines are awful. There is still writing talent at the company, the people who write the questing level content can still make good stuff. But the overall story is laughable, it's even worse than the pro-fan fiction books they've been churning out with people like Golden. And that's saying a lot, that the official game writers are worse.
Wow has always been a shallow pool when it comes to story - Metzen did a credible job pulling it all together, culminating in the Chronicles, but Danuser just stinks on ice, with being creepy about it as a bonus. Might as well change it to "World Of My Queen Sylvanas".
I won't even try to explain how dumb "let's storm the afterlife for lootz!" is. You either buy it and hold your nose on the hamster wheel, or you don't. Of all of the cool things they could have done taking the game into a completely different plane of existence, they just churned out 4 zones that look like every WoW zone since the beginning of the game. They took the player to the afterlife, where mortal rules don't matter. They did little to show that you're not in the living realm anymore. You could throw the new zones onto the Legion map, and there'd be no disconnect at all. The maw i just an unfinished Argus.
I'll stop there. i played the beta, I could go on quite a while on it's flaws. I saw how shallow the story is, but it's lower on the list of reasons why I gave it all a hard nope.