This is a very controversial topic that you have brought up: Freedom vs. Safety.
Personally I think that the law should require all people to wear helmets, because in the long run we are saving lives. I feel like a helmet for a bicycle is like a safety belt for a car. We have laws requiring us to wear safety belts, and therefore it is logical to have laws requiring us to wear helmets. In this situation, I believe safety precedes freedom.
However, I see the argument for having the freedom to decide whether or not one wants to wear a helmet. We live in a country based on freedom and therefore everyone should have the choice to decide if they want to wear a helmet or if they do not want to wear a helmet. In this case, I would hope that everyone would choose to wear a helmet, because I wish everyone to have a long and safe life.