Quote Originally Posted by Zakon View Post
Right, the retconned version to explain why we're allying with him again in Legion.

Because they definitely had that planned all along, and it was all well told within the game's story and not something people had to put together over time. Which is why Illidan was trying to destroy Shattrath because... reasons. And why Akama wanted to rebel against him.

Which is really all just to explain why his character got destroyed between TFT and BC in order to make him a raid boss because he has name recognition.
Uhh... most of this was said during the Outlands quests + BT pre. You just have to read quest texts.
I didn't play Warcraft 3, I didn't spent hours browsing the internet for information as I was still fairly "new" to WoW by the time BC hit and I knew almost all of what he explained. Many quests not directly related to Illidan or part of the BT-pre gave a lot of background information.