Why does the nightmare frontier concept art look so much better than the actual area in the game

The locations in bloodborne are usually very accurate to the concept art. I find odd how different nightmare frontier is from the art. It looked much better in the artwork, but.. not very good in game

The locations in bloodborne are usually very accurate to the concept art. I find odd how different nightmare frontier is from the art. It looked much better in the artwork, but.. not very good in game