The only reason, to me it no matter how it is created, is to stop reflections from giving position away, or you would polish it. It does not add protection. Under the wing does look intentional but to me the cowl looks more random and less staged. One done to match the other? There was a decent pic on the Aerodrome as I dont have the Data File. It is probably a little in between recognizing the effect the rough metal had and going so far with planishing then finishing it. An Obscure factory picture would sure be handy for yea or nay.