I just don't like the way they feel, they're clunky and uncomfortable, let alone the fact I don't see how that block of Styrofoam is going to prevent me getting injured, I'm pretty sure not that long ago a study was done where a neurosurgeon said he sees no difference in a lot of cases between the ones with and without helmets, I wish I could find that video online but I couldn't. So, not only would I not be willing to wear one but it was the determining factor in me not owning a bicycle as an adult, I just can't do it. Although, recently they repealed the law for anyone over 16 years, but living in a metro area it's too dangerous to ride anyways.
If I knew I was going to have a wreck and hit my head, I would want to have a block of Styrofoam strapped on. It's just that the same logic argues for kneepads, eye protection, a bullet-proof vest and carrying a lightning rod. I believe that helmets reduce risk of injury in some crashes. They do a good job protecting against less serious scalp injuries, help protect against direct-impact brain injury, though apparently are not so helpful with brain injury caused by rapid twisting of the head during impact. The problem with interviewing neurosurgeons is that you don't hear about the people who didn't make it to the hospital.