I always wear a helmet while riding, but I don't think it should be the law to do so. I don't agree with the seat belt law either. Personal safety should be one's own choice.
I'm kind of with you on this. I think it should be mandatory for anyone under 18 to wear helmets though. And seat belts for that matter. An adult can choose for him/herself, but children should be protected at all costs.
Where I have ridden, and will ride again, it's mostly just cars you have to worry about (which is bad enough). It's pretty city there. But Nancy is right about wildlife and other hazards. I always worried about rocks popping up and hitting me too. I had one hit me in the eye (I was wearing sunglasses, so no harm). But, you never know what might pop up smack you upside the head.
My dad hit a deer once when I was a kid. He was Ok. Just kept on riding to work. He called it in to the Sheriff, and by the time the Sheriff got out to where the deer should have been it was gone. So, I guess both parties were lucky in that one!!