I honestly think we should completely eliminate the idea that bras are necessary anywhere. We all have nipples and sometimes they show more than other times. Who cares? Bras are not comfortable and I don't think they are really healthy. You want to wear one for support? That's cool. I don't need one for support? That should be fine too. I would honestly be perfectly okay going into my business casual office with no bra, and to be honest, often went without while waiting tables because to one could tell. If I'm wearing a heavier top, I often go without in public because I can and I prefer it.