i have a bike and the law requires me to wear a helmet , after 10 tickets now I am careful when i drive with out
to answer the original question, i can not see any possible scenario where wearing a helmet on a bike would endanger others... so the only person in danger is the driver
now then we end up being to the question: should suicidal (risk taking) behavior be legal if the only one being hurt if your self ... my opinion ABSOLUTELY YES, you risk death its your problem... although if you (or i) do not wear a helmet health insurance should NOT cover the injury !
secondary problem, your in an accident and its NOT your fault, in this case should the insurance of the other driver cover the damage to your head ?! this is a very BIG issue... my personal opinion is that NO it should not.. but i do understand that this is very controversial, because if the other driver have not caused the accident helmet or not you would not have the injury
and i think that's the main reason helmet is required, the damage to insurance companies !
i will continue NOT wearing a helmet when even i can get away with it ;)