I think its more a case of the original 5 devs couldn't hope to compete with the AAA graphics, so they made a more stylised look and worked on the environmental effects like lighting and weather effects... plus it keeps the game size reasonable.
Overall I think the looks are good, at times it makes me just stop and look rather than just work through the content like most games, I actually stop and just admire the effect.

A cheap effect done very well, has more impact than top level graphics that are just technically good but these days rather blase, imo.