Hmm...I would be open to an alternative.

But what I've got in mind is: if someone were suddenly to acquire an extra 100 flaws, this would indeed be a loss; they would feel worse walking down the street as people glance at them, they would lose social status, people would judge them as less honest, kind, intelligent, etc.

So they are losing social status and they're losing other people thinking well of their appearance, and like any other loss will tend to fear it more than they would value gains of equal size.

And that's what people DO experience, in a less dramatic way. You could say, perhaps, that it's because we have the ability to alter our appearance that the problem exists, because sometimes we look better than at other times, and we'll tend to focus on the flaws that make the difference.