I can see you're point but I think the way they are "made" on the RS6 is much better than on the Impreza.
I also think that Impreza isn't a good car as the EVO's.
So..
I have a friend that has a Subaru Impreza.. I actually haven't tought about the fact that he's got those wheel arches. you don't really notice or pay attention to them - you rather drive the Impreza than look at it. It's not a pretty car. (IMO)
but on the Audi.. it's just
(Take the best that exist and make it better - RR)
Edit: And of course the old quattro got them