While i agree that the art style has changed you have to remember that A LOT of the old assets were just placeholders most likely. I do like some of the older styled assets though but also some of them would be very out of place when placed next to some of the newer assets that basically NEED to look better otherwise they would look strange or even unrecognizable. Maybe when the game releases we can get a "texture pack"-ish setting to bring back the "classic" assets.