Being told to wear a bra has zero to do with the oppression of women. If anything, it's the opposite, by turning something that has nothing to do with women's issues into one, it makes real issues seem much less reasonable.
Think of it this way. Man or woman, is wearing torn shorts and a tank appropriate attire for going to court and arguing your traffic ticket? Is it appropriate attire for your attorney to dress that way? Or is your 'relax on your day off' attire more appropriate when you go to the store or a restaurant and you should dress in a more formal manner when pleading your case? Speaking of the store or restaurant, do you go barefoot or (for the guys) shirtless because you're comfortable that way, or should you dress for the rule "no shirts no shoes no service"? When going to church, do you dress in a manner that's respectful for the sanctuary, or is it bootie shorts and a death metal tee? If you get a job at Cracker Barrel and you have a full sleeve tattoo, do you wear a long sleeve shirt per their no tattoo rule or do you go in wearing a polo? What is the definition of casual Fridays in an office? Bottom line, there are a lot of settings where uncomfortable clothing is what's appropriate. Ask men about ties. Ask men about ties when it's 95 degrees. If some women don't find bras comfortable then when they are on their own time and they are not at work or in court or another place that has certain dress expectations then who cares if they go without. When in a setting where you have to present some amount of professional appearance put the darn thing on and thank your lucky stars that you are not a guy attending an outdoor formal wedding in August in Texas.