As for men being shirtless, I am one person on "the left" that wants to see more of it, not less. I think men that spend so much time and energy to look like Adonises should take their shirts off and show off what they have. It's good for community morale to see healthy men
.
As for women, breasts are normal and natural, and there's nothing wrong in my opinion with a topless woman on a hot day hiking up a hill, or on a beach trying to stay cool. It's just fine to me.
but have respect for families with kids though - I think if I had a child I would not mind them seeing a topless person on a hot summer day, but there's others that would not want the children to see that due to them feeling its "improper" or "inappropriate", so there should be a level of respect for those that don't want to see you without the right amount of clothing.
I feel as a society we've become so much more casual. In the year 1950, I bet it was very odd to see a guy jogging around a crowded neighborhood without a shirt. Today, in the summer, you see it. It's a different time.