That's true, society is a huge part of women not being able to walk around shirtless. In some African cultures, for example, women walk around without a top on and breastfeed their children in public and nobody bats an eye about it. I'm not one of those type of guys who walks around without a shirt when it's hot, and I probably actually fall more in line with your second to last paragraph, not really wanting to walk around shirtless at a beach/pool but feeling stupid if I don't, because guys are supposed to.
I didn't really think about it in terms of temperature though. Generally when I see a guy walking around without a shirt, normally I tend to think "What a douche" moreso than "Oh, it must be hot out". But true, my own brothers take off their shirts when it gets hot out, so I can understand the want to be able to do so. And that really is too bad that women can't. I mean, I guess a woman could walk around in like a sports bra/shirt or bikini top, but even then it's not the same (plus they'd have to worry about possibly being stared at).
It really is kind of weird that breasts have become such a oversexualized and romanticized thing. I mean if you want to get "technical", it goes back to primitive instincts, and men wanting to find someone who would be able to nourish their potential children. But for the current culture, it makes no sense. And I totally agree btw, I don't see how breasts could "corrupt" a child, and anyone who thinks so needs their head checked. Sorry if I gave off that impression.
And no worries, I didn't think you came across as angry/aggressive. And it's nice to get a female POV on the matter, too.