Its simply a common problem in nowadays sexualized sociality.
What exactly is the problem with a mother feeding her baby - okay you see the breast but you can see that nonstop from morning till night nowadays.
In music videos, movies etc. to sum it up: Sexual stuff everywhere.
So I dont really understand why seeing a breast is so unnormal in first place, especially when its something harmless.
I think people just reduce it to a certain fact -> being dirty/cheap
I've never seen it in public but even if I do it should not take too much overcoming to look somewhere else.
I wouldnt mind at all. I rather question the outfit of most female teenagers where they show their breats on purpose.
In the end everyone thinks different about it though! ;D