Honestly with modern medias need to give basically every villain a sad sob story I can almost respect a villain who's just a bastard-coated bastard with bastard filling with an an order of bastard on the side.

…Mind you, I've never read/watched MHA so I'm not sure how much my take counts for in this specific instance ¯\(ツ)/¯

"He's irredeemably evil, but far more damningly, he's just boring."

… But isn't that his point?
The Joker in more entertaining cause he lives for the cruel dark humor his actions creates.

But AFO isn't here to entertain anyone but himself.

That's his personality, a pure asshole that wants the planet for himself.
And instead of charisma, he uses his powers and resources to make one sided deals with normal people like a demon.
And he has no redeeming qualities cause he doesn't want to be redeemable. He just wants other to follow him and torture does that don't.
And as basid as his backstory is, "I just want to rule the world", that's what he is. Pure evil. A monster in human fresh that's horrifyingly efficient and capable of planning ahead.

Maybe that's boring to you, but to others he has done a good job at being this ultimate big bad that WON'T stay down.