What is really important to note here is that the original Beyond Good & Evil is right about to turn 13 years old. 13 years. The game looked as cartoon-y as it did when it came out, as that was basically the best that could be done on the available hardware with whatever budget they had. Of course a sequel 13 years later is going to reflect a new art style that meshes with the leaps and bounds technology has made since the hardware the original released on.
Hell, going more realistic may help to sell the concept and ideas they are aiming for in the sequel, and even then, concept art is just concept art. They'll ultimately go with whatever looks best to them when brought to life in the game engine. I doubt this game is going to have a AAA budget either, so I wouldn't expect gritty and hyper realism in the final product anyways.
