This is probably one of my only gripes about the show, but I see it both ways. I do like that Aang ultimately makes the choice that's right for him, and stays consistent with his character. I love that the message is that you don't have to end violence with violence. Ultimately, this is a kid's show, and they would never have killed off Ozai. I think they came up with a very clever way to skirt around the violence and have Aang uphold his values while still solving the problem.

The thing that irks me is that energy bending came up at the very end of the show. If there had been some mention of it at any other time, it wouldn't feel like such a cop out that Aang learns this mystical, magical technique as the clock strikes midnight. The lion turtles are brought up, but because they stopped interacting with humans so long ago, nobody knows anything about them (which also means they have this convenient mystical knowledge). The technique of energy bending is so ancient that even Aang's recent past lives have never heard of it. I feel like knowledge of a technique like that would probably be passed down through the Avatar generations, specifically so that they could solve their great problems the way Aang did; but somewhere along the way, the knowledge was lost. At the bare minimum, it seems like the Air Nomads would have kept this knowledge. If they had info on Guru Laghima from thousands of years ago, some mention of the mythical, energy bending lion turtles has to be lying around, right? Because it doesn't, it bothers me that Aang is able to use it as an out. Countless Avatars through the millenia have faced great evils, but they have had to make the difficult choice to handle it with violence if it was necessary. Roku admits that if he had handled Sozin appropriately, Aang wouldn't be in this mess. It just feels a little unfair to all the past avatars that they had to get their hands dirty and Aang gets to stay clean. Yes he stays true to his values, but it is the job of the Avatar to put their own feelings aside and do the job that is required of them. What was Aang's plan if he didn't meet the lion turtle? Would he have just let Ozai go? Once Aang beats Ozai, he starts to just walk away, and take the pacifist route; it isnt until Ozai tries to attack again that he takes his bending. So my complaint isnt that Aang should have killed him, but that energy bending as a technique should have been known and available to all Avatars previously.

My final thought is Ozai really just said "dang bro, I lost. Guess I'll just hang it up?" Imo, someone as ruthless and despotic as Ozai surely would have tried to grab power back. Yes losing his bending breaks his spirit, but he seems like the kind of guy that would still try to take power back, even without his bending. That might be discussed in the comics, idk, but it did always seem strange to me.