I don’t know how you could link a culture’s relationship to breasts with its effect on the quality of life of that culture. You could compare cultural attitudes towards breasts, and you could compare quality of life—maybe. You’d have to find a way to measure quality of life. There are such measures, but I don’t know how good they are.
Correlating breast fetishization with quality of life, or seeing how much of a correlation there is—I doubt you’d find a relationship at all.
I suspect that for cultures that make a big deal out of breasts—they probably build industries oiut of them. They are a sign of status. Need to have big ones.
If breasts are “normalized,” whatever that means, then they would be less important, and probably the society would be more laid back and more boring. I’m not sure that’s a better quality of life.
I think life needs an edge. Things are more interesting when there is a disagreement about them. Especially when a lot of shame is brought in. Then people who disagree with the prevailing norm can sneak around doing something different, thus feeling like they are getting away with something. I think that kind of turmoil is more interesting and probably increases the quality of life.