I had a discussion about this in class a while ago. It was pretty thought provoking and I'm still thinking about it. It was about what life would be like without a mirror or light reflection to show us what we look like. The question was brought up, Would you be the same person you are now if you never knew what you looked like? How would everyone act if they only knew what each other looked like and not themselves? You could look like anybody for all you know, so how do you know if you look different than the people you see?. You don't..it would be a mystery and also give the illusion that we are all the same looking. Yet in reality we aren't the same looking.
You can know that you look different than other people due to the reality. When there are two people standing in front of you, you tend to differentiate what you observe. You can analyze it and conclude those two look different in physical appearance. Imagine observing 50 people. The reality of it would be they do look different. People would still discriminate and judge life as separate. You can also look at your own body(Skin, skin color, muscle, fat, defects, etc), not just your own face. The reality of the situation is that if people categorized you as butt ugly in physical appearance. And called you names as such, you can't determine it as true(in your P.O.V). But since everyone doesn't know what they themselves look like, discrimination would be around less. Then again when negative emotion fuels, people have the tendency to discriminate and view things as separate.
For me it probably wouldn't change all that much. My self-image has typically hovered around neutral. Even looking at myself I'm not entirely sure where I fit on the spectrum. But to answer your question, it would basically make everyone's self-image a democratic process. In our real life scenario "beauty in the eye of the beholder" plays itself out. There are those "hot" girls out there some guys point out, where I just don't see it. There are also those I think are gorgeous but have a very low self-image. Beauty's more subjective than we usually admit. Visual manipulation and "ideal" images have probably impacted our perception of what's attractive just as much as our ability to see ourselves, if not more. We probably get most of our critical nature from being held to an ideal that is unrealistic. Another thing to consider: if you're not a person who looks at photos of yourself, the image might still not be complete. A lot of people (myself included) tend to prefer their mirror image.
Its like playing an FPS game. The mission is the only thing that matters else without a duty you're just standing staring at the landscape
It is pointless to discuss what if theories, it is not the reality and truth of things. All it does is provoke ongoing waves of thoughts. That manifest and dwell in your head.