I don't know, to be honest, but I think I prefer black (perhaps matte black) when it comes to the wheel arches. I think that, depending on "hull" colour, it might be a bit too much having them in the same colour. Black at least matches the rubber and spokes.
Maybe the designer had an idea that it should have a fender-less look...or? With black fenders tightly following the curve of the wheel it actually looks a bit like that from a distance.
