Still not buying the Ozai had dimensions argument. His children did. He didn't.
That's because you frame dimensions as "good/bad" qualities. Dimensions means you have an understanding of how he came about as a person. He wasn't doing evil acts for the sheer pointless dickery reasons like Unalaq was. He was a rare, realistic depiction of someone who lacks empathy and an understanding of compassion works, which frames different actions that are still fundamentally evil in a more human light. But people think humanization is an invitation to agree with him to some extent.
Hold up homie, but where and when exactly? I don't remember ever coming to give an ounce of sympathy or understanding towards him at all.
Yeah, see? To be humanized doesn't mean to feel sorry for someone. It does mean to have empathy for them, but people take that to mean support in some way, and that's not it either.
Edit: I'm tired and falling asleep, but I'm sure you can find my posts on Ozai by searching.
I'll only add this in an attempt to try to explain what the world from a sociopath is like. This is a rather bad analogy, but bare with me.
Being a sociopath is like being forced to drive a car that has no breaks, while not knowing that there SHOULD be breaks in a car. To be a sociopaths is to lack the ability to feel empathy, which means you miss many social cues that others get that allow for an effective way of interacting with others socially. And only the clever ones figure out that they're missing something. Ozai being the Fire Nation head never had any need to learn social cues, so he's a sociopath that has no idea that he's missing a key feature that comes with typical human beings.
What gives Ozai a humanized depth to his character isn't that we're invited to sympathize with him, but that he functions not as a villain, but how a real person who lacks the ability to empathize with others would act. So, for example, when he burned Zuko's face off, he later justified it as a way of trying to teach his son respect. If Unalaq would have said that, that would have been a deflection or revision of what happened, because Unalaq is a generic bad guy. What makes Ozai different is that he meant it. He wasn't being actively malicious. He was actually, truly trying to be a responsible father. "My son performed a wrongful action, which requires discipline." But he lacks empathy, so he goes way, WAY overboard, because he doesn't understand what anyone with normal functioning empathy would: that Zuko isn't learning proper military etiquette, he's just a scared boy who doesn't know what he did, and in an unreal amount of pain. But Ozai doesn't have empathy, so the signals that we understand don't get through. He car breaks are cut and he doesn't realize that he wasn't supposed to crash into another person at high speed. He thinks that's just what your supposed to do.
This is also later reflected in his actions with Azula. Azula loves him. But he wants to rule to world alone. So, how do I do that while also rewarding his daughter for her service, he thinks to himself. So he dumps her with the fire nation. And you know what, he's right, that is a fucking monumental reward for a job well done. He doesn't get that she doesn't care about being a ruler. She wants to be with him, on his side. Again, the social cues that should be obvious as he would know his own daughter better than anyone, one would think, completely go over his head. He's not trying to screw her over. He's trying to do right by her. But he doesn't have the tools to interpret social cues that would let him know his daughter doesn't want that, so he doesn't realize his error.
This is not an invitation to 'sympathize' with him in the sense of "oh, poor him, he just doesn't know he's evil". You could look at it that way, true, in the sense that he didn't choose to be born wrong and in an era where he cannot get the mental help he needs. It's the same pedophile argument about how none of them choose to be born with attractions to children. True, but this is beside the point I'm making. It's the fact that he is what happens when a human being doesn't have an important social tool that allows him to interact with others. Without this tool, it doesn't matter that he is
trying to be a good father to his children any more than a man whose car's breaks are cut is trying to be a good driver. You need those things to be effective at those tasks, and Ozai just doesn't have it and any attempts at 'doing right' in his eyes end in disasters that he is utterly oblivious of. That's the great irony of everything about him. He traumatizes his kids trying to be a good father and is oblivious to it all. But he's not trying to be evil, the same way no one in real life ever tries to be evil (though I guess groups like ISIS may dispute that notion). What he's actually doing is the same as what any other people do, trying to teach his kids about the ways of the world and rewarding them for their efforts. Do his duty as a father, in other words. But he's a sociopath, so his deficiency means he can't see what he's actually doing.
This social blindness comes up other times. For example, he asks Zuko to describe the Earth Kingdom, and Zuko does so with obvious respectful inflection in his voice. But he framed the question around how to defeat them, so he missed the obvious social tone, and focused on the words themselves, and responded with a tacticall strategy (as that was the relevant subject at hand). He also tries to take over the throne by pointing out his brother's grieving, as he thinks in pragmatic (Or, in this case, predatory) terms. Suffering = weak. Weak = bad. Therefore, asking father to allow him to supercede the throne is a reasonable proposition as only strong should survive. He doesn't think to consider that his father might ahve empathy for his other son's suffering, and take offense at such a suggestion.
You'll notice that all of these things still result in evil actions by Ozai. As I said, I never intended to sympathize with Ozai. He's an evil bastard. But he's an evil HUMAN bastard. Sociopaths, at the best of times, learn some measure of intellectual empathy by interacting with people not as a means of connecting to their emotions, but a simple and endless series of trial and errors of what produces a good response and what produces a bad response to understand that they are missing a vital component that prevents them from normal socialization, and they need to compensate for it somehow. Sociopaths who have unimpeachable power however? Oh man. It's like leaving an alcoholic in the worlds largest liquor store and telling him he won the booze lottery and it's all free for him. Normal people become socially maladjusted when they have an unchecked measure of power (spoiled children, corrupt cops, etc). How do you think someone who has a lack of empathy will handle it?
Ozai is predisposed to evil the same way a person driving a car with cut breaks is predisposed to crashing that car. And that's the real human factor. Ozai isn't a monster just because he's a monster, He's a monster because, as a human being with that deficiency and that position of unlimited power, what else can he be?