Ya’ know what I think?
I think that we should all just go about in the bare minimum of cloth it takes to protect the delicate flesh of the nether regions of our personal universes (unless, of course, you live in chilly climes, in which case the near-nudity would be confined to indoors, or to the summertime).
After a generation or two, the sight of a pair of shapely breasts (or buttocks, for that matter) would be no more exciting to your average male than the sight of a hand or foot.
When this happens, there will no longer be any need for discussion of whether high-spirited breast flashing has become a socially acceptable form of behavior.
The truly daring among us will then drape ourselves with cloth in order to create a sense of mystery, which will then become more exciting than high-spirited breast flashing ever was.
And the whole thing will start all over again.