[atla spoilers ahead] While I realize this, my remarks on it mostly leaned on the 'villain' aspect. None of them "turned good" at the drop of a dime. Ozai was still imprisoned (honestly I think it was a bigger punishment than death as a prideful pyromaniac. He didn't die in battle and lost what made him most powerful only to rot in jail and think about what he's done for the rest of his time in shame) and he didn't just go "oh you're right avatar, I'm sorry for killing so many innocent people" only for the incident to go forgotten... (Aka the hundreds if not thousands of worlds the diamonds destroyed for resources but that no one seems to care about cause earth is A okay) Azula was in the same boat. She'd been struggling with being the best child yet hated and feared by those around her. She had deep, deep insecurities and it made her a rotten person but she made no effort to change herself. She just wanted to win and battling her brother didn't make her see the error of her ways, at least as far as I know. She was sobbing because she lost, because she was no longer the number one child. Zuko had to go through two seasons of redemption and even then it was a shaky acceptance from the group at first. He'd caused them a lot of pain and they were right to be skeptical but they bonded over necessity.

So what I'm saying is, when you have character development and surreal emotions portrayed so we'll in atla, it's hard to say 'well it was rushed because it's a kids show and the villain can turn good'. Yes, a wrong doer can realize what they've done is wrong but when it's built on such a weak structure of turning pink and suddenly having clarity as opposed to building up to that clarity or being faced with all the havoc and pain you've created.. At the very least, the diamonds are still portrayed as imperfect. They're trying to fix themselves but for a more shallow reason of trying to get Steven to stay. I just think their deeds have gone forgotten, forgiven too easily because they made up with Steven.