I can't say that I've completely made my mind up either way, but I definately think there's merit to what the OP is saying.
About
Isabella... In this
thread Darkhour posted a revamp that I think illustrates quite well how Isabella's face could be improved.
http://img841.images.../newisabela.jpgIt's not about her being ugly in the original build, but her face not being porportionate to her head. The chin does seem too large, the lips a bit too small and the cheeks a bit too full cosidering her head and the rest of her body. It might be that some people don't see a problem with it, but I believe the revamp looks a whole lot more realistic. The original face just looks like the facial features have gravitated a bit too much toward the centre of the face, making the cheeks and chin stand out.
Aveline on the other hand. I don't think we've seen enough good pictures of her to really decide if she looks good or not. I said good, not pretty. Not asking for her to look like a modell mind you, but at lest you shouldn't cringe when you see a companion. Unless that's the desired effect of course (Spirit of Justice anyone?). Her concept art doesn't do her justice I'd wager. She looks like a warrior and that's cool, but in my mind she looks a bit too buch in the concept art... Like neanderthal butch. The screenshots however, make her look much better, so I'm not really worried about her.
So yeah, I don't think it's fair to start making accusations that the OP wants all female characters to look like models. There is something offputting about Isabella's face, and I don't think it was intentional from the developer's side to give her a unique look. I think especially if we're talking about love-interests there's nothing wrong with wanting them to actually look appealing. In the end it's the personality you remember and love, but looks are always a plus, just like in real life.