Mandatory Helmet Laws

Should helmets be an optional accessory, rather than an absolute requirement? Or are helmets a sign of a culture not yet ready to embrace biking as a normal, safe activity?
May 19, 2014   Vox
Elisabeth Rosenthal reflects on the deterrent to cycling, and the use of bike-sharing systems, posed by mandatory bike helmet laws. Does the rare serious injury prevented by a helmet outweigh discouraging cycling's wider health benefits?
Oct 1, 2012   The New York Times