MoP is often remembered now as a pretty beloved expansion. And it deserves its good reputation. However, at the time it was full of controvery. I’ll start with the most obvious:
The theme
I remember opinions were heavily divided at Blizzcon when they unveiled Pandaria at Blizzcon. We went from slaying demons, to battling undead, to defeating the worldbreaker, to hanging out with pandas? People genuinely believed this was the point Blizz jumped the shark and gave us a filler expansion.
The story
When we entered Pandaria, we didn’t get any discernable goal. We’re just exploring and fighting the other faction. We encountered the Sha who were creatures made of feelings, and that felt cheesy. Blizz spoiled that Garrosh would be the last boss, and to many his corruption arc was too out of character for him.
New talent system
Oh boy did people fight this. I vividly remember people arguing that “meaningful choice” was just showing us 3 core class abilities and forcing us to lose 2 to pick 1.
World questing
People were overwhelmed with the raw amount of dailies at the start of the expac. Blizz said we’re not supposed to do them all, but people weren’t going to self regulate. It was a terrible rep race. There was also controversy over the future quest hubs because they had no flying, but instead had jumping puzzles and tightrope walking.
LFR
MoP began with LFR and as such it was at the peak of the LFR debate. Back then, LFR had much better rewards, and it was essentially a gearing stepping stone. You needed a very understanding guild if you wanted to skip LFR loot and go straight to normal.
Legendary cloak
I’m pretty sure there were more controversies over the cloak, but I can’t remember them. I do remember people refusing to get the cloak because they didn’t want to do the PVP part of it, which was 2 BG wins.
The subs lost
This was the main evidence people posed for MoP being a failure. Each quarter we’d see new numbers of lost subs, and people would go “HA! I told you so!”
Anyway. That’s all that comes to mind. I still think MoP was a great expansion, but back in the day it was highly controversial. I can’t think of an expansion that sparked as much controversy at the time. Yes WoD and BfA were hated, but everyone agreed they’re bad, so there wasn’t much to debate there.