The story isn't bad because the devs are lazy. It's complicated, but one observation: they're trying to tell a "great man theory" esque geopolitical intrigue cosmic war tale in a world that isn't reactive because of developer resource constraints.
But which I mean: a hole in the sky into Hell (literal, actual Hell) opens, through which demonic angels fly and kidnap the leadership the Alliance and the Horde.
And no one gives a shit. Did anyone on Azeroth notice? Does anyone care? Thrall, Jaina and Baine don't seem to care, they're just sitting in Orobos, swapping stories about how much it blows to be tortured endlessly by WoW Satan in his literal Tower of the Damned.
Also
1) pretty sure marketing foists plot points on the dev team (ie bring Illidan back!)
2) pretty sure shadowlands had cut content, and what we did see was reworked
3) the idea behind Shadowlands isn't that bad, if unoriginal even by WoW standards- the problem is they mystery boxed it. What did the Jailer say to Sylvanas to convince her? Buy the book, released after the game is finished, to find out!!