In my experience, I think it is best to let the riders decide. The first, and probably obvious point, is that the only victim of a bike accident is probably going to be the biker. I don't know that we need laws protecting us from ourselves.
Secondly, this article is completely correct. I never wore helmets when I was young. The only exception was for BMX biking over jumps and all. Even at a young age, you understand the importance of self preservation. Today, I wear a helmet when I am mountain biking or when I want to better condition myself for wearing a helmet while mountain biking.
Otherwise, I prefer to leave the helmet at home. I've gotten heat stroke before (while biking on safe roads) and I will say that it was far more dangerous than any accident I ever sustained on a paved bike path or road. And helmets do make your head a little hotter. Besides, when you are on a safe trail or road, it's nice to feel the wind on your head and just feel closer to your surroundings. Biking is for more than transportation, it is for the joy of the ride.