Originally Posted by
Wildmoon
For Jaina's case, there is at least the cause which led to her recent actions whether you think it's a good direction for her character development or not. For Maiev, I am still waiting for Blizzard to really explain what really caused her to do what she did in Stormrage but to me using the corruption trope again would be stupidly cheap. I also think her actions in Stormrage were not that strange too. She showed a sign of being crazy since WC3.
Illidan's case is just downright stupid. Blizzard just can't comprehend that there's no need to retcon Illidan into a good guy to actually shine spotlight nor redeem him as a character. There's this character called Alarak who assisted the protagonist of SC2:LotV, Artanis. He is just a twisted and evil dude but he is still a likeable character and well-liked by the community.