This is definitely the way I've always read the 'scar' trope. I'm sure there's a level on which it is a body image issue for some writers (and, maybe, I think, tied into the fact that chances are the characters we are writing about are depicted in canon as more than commonly attractive, so even if we only think our own bodies are 'okay' or 'average' the characters are probably hotter than we are -- so the only way to give them body image issues is to focus on wounds-as-imperfections. Which, depending on the context CAN teeter into disability-fail, but is usually just 'sexy dude has a long-forgotten-by-canon bullet wound that's usually covered by his shirt). But I've always mostly seen it as a physical standin for psychic damage.