Here in California the helmet law passed when a weak governor trying to score points signed it into law in 1992. There is no doubt that wearing a helmet can save your head, but it should be the riders choice.
As far as the "public burden" excuse for passing this law, mile for mile you are safer on a motorcycle and more likely to receive head trauma in an automobile accident since they are driven more miles comparatively.
Also it has been found that the sturdier the helmet, the more it weighs. Part of Newton's first law is a body in motion tends to stay in motion. In the dynamics of a collision a helmet's weight can cause spinal injury as it continues at the speed it is traveling after your body has come to a stop. The only "brakes" it has is your neck.
And finally, don't forget that Christopher Reeves was wearing a helmet when he fell off that horse. He was paralyzed by compression to his neck.
LET THOSE THAT RIDE DECIDE.