When I returned to cycling after many years out it was into mountain biking. That was new to me and quite risky so I decided to always wear a helmet. The falls often included a bump on the head, sometimes into branches but one against iron railings and another on a hard floor. The second time I woke up, with my bike alongside me, in an ambulance to the hospital where I was diagnosed with concussion which included some bleeding in the brain. The helmet was totalled. Logically, or illogically, I believed that it saved worse injury so for me there was face validity at least in their effectiveness.
I never had a helmet when I did a lot of road riding in my teens and early twenties, but when I started road riding again four years ago I decided to continue with the helmet wearing. It does not feel uncomfortable at all, in fact I have forgotten to wear it a couple of times and did not notice, and I never have the arrogance to tell tell other cyclists, male or female, what to do about helmet wearing
I cannot understand all this aggro about wearing or not wearing. It's your head so do as you see fit about what you put on it. As far as preaching is concerned it seems that both sides are more than a bit preachy about it. People in falls without a helmet say it saved them from worse injury, while people without helmets say that their lack of a helmet saved them from a broken neck.
All conjecture, as it still will be ten years from now.