Hey, it's a free country. Or close. But to me it really is inconceivable how a bike-commuter would elect, choose, opt to not wear such a safety device.
But I won't flame someone who doesn't agree with me.
In my experience, however, the "no-helmeters" are also the same types that travel the opposite direction, have no lights in the dark, ride on sidewalks, and generally act like absolute rookies.