I think, it's funny that they have the paper aesthetic going just because Paper Mario did it. Copying the gameplay makes sense but there's no real unified aesthetic sense for making everything flat
But then I think, this is also true of Paper Mario, which was called Super Mario RPG 2 in production for a while. The paper was just a visual gimmick that was only incorporated into a larger sense of physicality in the installments, when they were starting from 'make a new Paper Mario.'
But then I think, okay but Bug Fables lacks the storybook framing device so it's still basically true