I hate "Asuka should have been the villain" posts
[Warning, lots of yap]
Genuinely surprised by the amount of people who believe Asuka should have been the series main Antagonist (Which he kinda was in a way, but we'll get to that)
From his earliest appearances, he's shown to be surprisingly chill or morally ambiguous at worst. In most of his interactions with other characters, he's very vague with his motives but oddly caring (like with Dizzy, Anji and Baiken in XX)
The only questionable interactions, I'd argue, are the ones he has with Axl and Eddie, and even then neither are exactly canon since both result in events that don't line up with later games. While he's blamed for a lot of crimes (the creation of Justice and the destruction of Baiken's colony), his personality and on screen actions are intentionally made to make the audience double think who he really is.
Come Overture, and it's apparent that Asuka likely isn’t all that bad, desiring to protect humanity from The Merciless Apocalypse, even if he does promise to settle the score with Sol when it's all done.
And from Xrd onward, once we get a real deep look into who he is and how he thinks, it becomes blatantly obvious that he's just a man who makes poor choices, based off his own interpretations on "what's the most logical thing to do here?"
He still very much did some horrible stuff (turning Sol into a Gear, Justice, blowing up Japan, making The Cube, etc.), but all his actions are made due to him being either pressured or doing whatever he thought was right in the moment.
The reason he played along with Sol's desire for revenge was to keep a connection with him and push him to grow into a warrior capable of overcoming the Apocalypse. It was also to take responsibility for what he did in the past, believing he deserved to be hated.
Asuka isn't an outright villain, though he's still responsible for a lot of horrible actions that brought about even more devastating consequences. Unlike Ariels, who actively wished for the erassure of all "redundancies", or Happy Chaos, whos methods of bring about drama to push people forward usually results in countless casualties, Asuka just makes mistakes and is stuck in his beliefs, viewing himself deserving of holding the identity of That Man, humanities greates war criminal.
He's a denier of personal growth within himself and is completely set in his world views, only recently being challenged by Choas' philosophy of necessity (pretty sure it's why #R is more open minded, though I can't remember the reason). Asuka is the antithesis of what Guilty Gear's overall message is, which is about personal development, understanding, and living for yourself. In a sense, he was the main antagonist, because he's the opposite of what Sol is, who is the heart and soul of the franchise.
To me, that's a lot more powerful than him just being the twisted sorcerer people wanted. That's just my opinion on things though (also please correct me if I got anything wrong)