The villains with actual nuance in this arc (or at least One Piece levels of nuance) are the Big Mom crew. We can have both.
Maybe one dimensional isn't the right word exactly. Moral nuance isn't exactly what I meant.
To point out one small comparison, lets look Bege. I don't think anyone would say that he's morally nuanced. He's a psycho on par with any in OP, his backstory has him creating pain and misery for seemingly no reason at all and his betrayal of Big Mom is motivated primarily by lulz. But when Bege notices that he talked about his plan with an animated door in the room, he killed the door. When the Vinsmokes talk about their plan to backstab Big Mom in a room
full of her animated objects that all work for her, they don't even
notice. They're too busy laughing over how they're assholes. That's the difference for me, they're not just evil, they're evilly stupid.
Alternatively, since the Big Mom crew is just better, maybe they're just making the Vinsmokes look that much worse by comparison. Then again, it's also probably just the Sanji relation that's screwing them over. Either way, I just don't see why they'd be anyone's favorites with everything else going on this arc. We have (sorta) intelligent antagonists for once who are Yonko no less that also offer personal stakes in the conflict by placing Sanji's conflicting feeling's as a key component of the conflict (as the strawhats being an external element to someone elses conflict) with some of the best designs the series has to offer....meanwhile these chuckleheads are being played so badly they don't even know how behind they are.
Edit: I think the power rangers comparison is right on the head, because Power Rangers weren't known for their political plotting. Once the fighting starts, maybe then that'll play to their strengths more.