there are social norms
As far as I know, there is no "social norm" that requires a woman wear a particular item of clothing. There are laws against public nakedness, but this was not what the OP asked us to judge -- and yes, she asked the MN jury, in her 1st post.
This thread is really depressing in the way that so many apparently intelligent, independent women accept so meekly and as a "social norm" a piece of clothing which seeks to shape them in ways that cover up, or disguise their bodies.
The brassiere, as a piece of clothing, is relatively recent. It's still not worn much outside the west. My grandmother rarely wore one: she'd grown up in the 1920s with the bodice or vest. A generation or two earlier, and women didn't wear knickers. They wore split crotch bloomers.
Promoting the idea that we all have to wear an item of clothing to hide an aspect of our bodies is promoting the limitation of women's freedoms, and condoning the judgement of women's behaviour in the light of what they wear. It's but a few steps to "Well, of course she was attacked. She was wearing a short skirt. She was asking for it."
It's the same mentality.
I might be light-hearted & joking about bra-burning, but there was a serious reason for women doing that. They were protesting against the judging of women by what they wear, or how they look; and the forcing of women's bodies into a pre-ordained & sexist notion of what a woman's body should look like.
You younger women have a lot to learn, and you should remember what women going before have done for you.