After many years without a helmet I now wear one and it has saved me from (at the very least) concussion. I would now urge other cyclists to consider wearing one but if I was in public office (perish the thought), I certainly wouldn't like to dictate that all cyclists should wear one. Seeing some attitudes though, I'm reminded of similar head-in-sand reactions to laws about drink-driving, using a mobile whilst driving, car seat belts, motor cycle helmets et al.