Only pro riders on closed roads should be allowed to wear helmets. They should be banned otherwise because they encourage people to take risks that they shouldn't and wouldn't otherwise take. New riders could just as well avoid scrapes and bandages with a good thick wooly hat.
I agree, same with seat belts and airbags in cars, and good brakes, windscreen wipers/washers, roll bars crumple zones and the rest - make a car like a death trap and everyone would drive so much more carefully - wouldn't they?