It might be popular because it stays true to the essence of Aang's character. Fans who love the original show and Aang's pacifist nature would be drawn to it as it explores that side of him further.
He could be really busy. If he has a lot on his plate, he might not have the time to check out your stories. For example, he could be swamped with work, schoolwork, or other personal matters.
It could be that he's not really interested in that kind of content or doesn't think it's relevant to him. Or perhaps he didn't even notice that you shared the stories.
There could be various reasons. Maybe he thinks stories without villains can be more unique and stand out. Or he might believe that concentrating on other elements like friendship or personal growth is more interesting to his readers than introducing villains.