I show a lot of cleavage sometimes. It makes me feel sexy and confident, I don't really see a problem with it.
We men can get in a lot of trouble comenting on this sort of thing. My thoughts are however you choose to discuss it be careful One of the things that we would all love is for women to be confident in them selves and their bodies.
I wouldn't want to tell a woman not to wear. However I wouldn't have problem letting my wife something doesn't match or give an opinion if asked but I don't think this is what we are discussing.
We are a bit older and have old fashioned ideas I guess my wife wouldnt dress that way out of respect for me. She has on occasion even told me to change my swimming trunks or shorts saying" you are frightening the woman and children" or" I don't want every one seeing what I am getting". And I think that is how I would feel too.
IT's great if you feel sexy and don't mind who stares at them because if you do have them on display like that you'll have to except people will stare. The whole bra thing is neither here nor there, if you don't want or like wearing a bra
you can still cover up.
A friends wife is flat chested but has very big nipples. She loves to wear thin cotton tops so they are very visible. It has come up in conversation. Her take is she is confident and happy and likes to flaunt them because it is so differnt. It does turn heads. She is very active and actually thinks that she is happier with out breasts as such, no bras , no having to choose carefully whAt wear. She has all so said that the nipples are very sensitive and she can if very aroused orgasm from them.
It would be very rude to try to control your woman. Encourage her.
My G/F has (as my youngest daughter (in her 30s) told me "the biggest tits she's ever seen" and occasionally she will cover up - for example if going to a halal butcher's where interpretations of the Q'uran impede normal interaction. I tell her not to worry, they are her body and she can do what she likes with them, although tbh if she covered them up too much I'd regret it. But I think she knows that.