Originally Posted by
Duckz0rs
That's why I resent him. He's an utter failure but can't admit it. He did all of these "good things despite the cost" to "fight the legion". Except in the end he does Kil'jaeden's bidding willingly at every turn of the way, telling himself that will give him the opportunity to strike eventually. His only redeeming action was at the end of WotA. Everything else was entirely self-serving.
But he's too scared. Kil'jaeden presented himself to Illidan within Outland, located in the Nether, meaning he has the opportunity to kill him for good. What does Illidan do instead? He cowers, apologizes for failing to stop Arthas and begs for forgiveness. Malfurion is often called holier-than-thou, but the exact same can be said for Illidan. He pretends to do whatever it takes to defeat the Legion, while constantly doing their bidding at the same time.
People like him because he's "edgy" kinda like the default bad boy in every anime ever (sasuke from naruto would be a good comparison).