I'm guessing the rationale behind the art is to evoke Mary Blair and midcentury Disney. Monkey Island was always inspired by Pirates of the Caribbean, and the film art of that era is a good cousin to that aesthetic.
My main worry is that they'll lose the feeling that you could step into the backgrounds and explore. Skewed perspectives can look cool, but moving Guybrush around on a semi-realistic depth field with winding paths is satisfying and makes the game world feel real.
As much as PotC gets cited, I'd bet Ron was a fan of Tom Sawyer Island. A whole piratey island to explore with cave passages, fun as hell! The first two MI games often felt like a simulation of this. I really, really hope the art and map-design of the new game are able to scratch that itch.
