I think there’s a difference between story and lore that many players don’t appreciate.
There’s a difference between reading The Silmarillion and The Lord of the Rings, just as there’s a difference between reading World of Warcraft Chronicles and Before the Storm.
One is intended as detached lore for the person reading, whereas the other is intended as immersive story through the minds of the characters who exist in the fictional universe.
Blizzard provides a lot of lore for players to better appreciate the story that’s being told in the game and the books and so on. But the story itself is supposed to be enjoyed on the premise that your character has not read World of Warcraft Chronicles and is not privy to the same understanding of events that you are. Tolkien does the same for his story and lore. Frodo never understands more of his adventure than what he learns along the way, because unlike savvy Tolkien nerds, then he hasn’t read The Silmarillion.
Beyond that!
I also think it’s a bit objectionable to say that Blizzard’s mystery reveals are unsatisfying when this is the modus opandi of Warcraft since forever.
What’s the first mystery that Warcraft presents? The Dark Portal!
Bunch of Orcs come through it all the time. Where do they come from? What’s on the other side of that portal?!
So what does the story do? Does it keep it as an everlasting mystery never to be solved? No! Next game there’s an expedition with Khadgar and Turalyon and Alleria and so on, that venture through The Dark Portal. Mystery solved! You get to see what’s on the other side. You get to see where the Orcs come from.
And then Blizzard does what they’ve always done when they solve a mystery, which is to introduce new ones!
Hey, look at Ner’zhul over there. He’s just opened a bunch of more portals to even more worlds! Gee, I wonder what’s on the other side of those? How big is this universe?
That’s no different from what Blizzard does today.
Gee, I wonder what death and the afterlife constitutes for on Azeroth? Oh, it’s the Shadowlands and there’s a Pantheon of Death? Mystery solved!
Oh, there’s also something about The First Ones and a Pantheon of Life? Great, now I’ve solved one mystery and gotten two new ones!
Welcome to Warcraft.
I would pose a question of curiosity when people say that these mystery reveals of late are unsatisfactory. Can you give some examples of earlier mystery reveals that have been satisfying?