|One thing I would to point out is that wasn't Aang who stopped Fire Lord Ozai from controlling the world by fire? Where would the non benders be if Aang hadn't?|
People seems to forget, it's a new universe and new threat energes. The thing is that, somehow energybending could have been a result to anyone wanting to control non-bender. I guess, the creation of gangs ruling the streets and corruption among the cities, is a result of Aang's death. Just like Roku or any avatar before, Aang makes a mistake trying to instaure a way to protect everyone, but he seems to have failed. Now that I think about it, maybe Aang uses his knowledge to teach AMON himself. But, Aang was hoping that he could use that knowledge in a good way. After seeing what happened to his father, maybe AMON tricked Aang and uses that power to revenge instead of instaure a justice. That could be another theory.