A fifteen year long French study has concluded that Bras don't actually work, that is to say they don't really do anything to decrease back pain or stop women's breasts from sagging. On the contrary they actually encourage it by causing atrophy in the muscles and ligaments that should be working to support breast tissue. I'm not really in a position to have an opinion on this myself, but it does have a certain appeal, why would the human body need a device that nature didn't see fit to provide strapped around it to stop it from going wrong? Is this just one more societal norm that people (in this case women) have been conditioned to accept? Who knows, maybe in the future we'll look back on women wearing bras as a strange practice akin to the corsets of the 19th century.
You can read an article written by an actual woman here: