It's emotional because people don't typically react well to being told what to do or not.
It can be rationalized on both sides of the argument.
Me? I grew up racing where the helmet was only for DH, then super-G. Mashing rapid-gates into your lips into your teenage braces was the norm. Faceguards became popular.
Fast forward ten years and then I've got kids. Now between the cycling, dirt bike riding, skiing, skateboarding, skiing and climing, our family of four has over 24 helmets. No regrets.
I've personally bashed my head so many times now that I'm stoked on helmets. And I've seen my kids fail-rail enuff to be glad I've got their melons protected.
I care about me, so I wear a helmet. I care about my kids so I make them wear helmets. The rest of you, I could care less about. Its up to you. But with an ER doc as a best friend and the long list of stories told of deaths and brainbramage resulting from lack of helmets is enuff for me to to be an advocate.