Something I've noticed in life is that people tend to be much rougher on a lot of things than history is. And it's weird seeing the turnaround.
I tend to just like what I like, but I remember, for example, FF9 being hated when it came out by the community (now it's looked at very fondly and praised as one of the "last legacy" FF games), the Star Wars prequels I remembered getting a lot of hate at the time but now people compare them to the new ones as positive, Star Trek: Enterprise was disliked when it was running but looked at pretty fondly now, etc.
When Mists was live, I was thinking at the time it was probably one of the better expansions the game had. Things were probably the most balanced overall in that expansion than they ever had been before (or arguably since), the world was pretty alive, I enjoyed the various content forms like the raids and the Timeless Isle (I think I was deployed during the Thunder isle, but it seemed to be pretty popular as well), and so on. It also has one of the most epic lines in gaming history to me:
"When I was young.... When _I_ was young......
...I was EMPEROR."
After that mountain climb with the old man, it was just such a powerfully delivered line to me, I still get a bit of chills from it.
I think it was probably the best or one of the best overall expansions in the game's history, it just took WoD and BfA and Shadowlands for people to finally make that realization, I think. A friend of mine and I were having a conversation at the time about it and he said the same thing. So some people did realize it, they were just drowned out by the negative nancies of the day, the people who always complain about "the current thing" no matter what it is.
Same.