It's also true that cycling goes down when people are worried about safety. Helmet laws and a focus on danger reduce cycling, which in turn increases injuries:
http://www.thestar.com/news/gta/article/641641
Anecdotally speaking, I've know people who have been spared tremendous trauma by wearing a helmet, and one girl in particular who's life was certainly saved by wearing one (she still ended up in the emergency room with a head injury because of the force).
Maybe me wearing a helmet increases the perception of danger, but hell, it's dangerous out there. Decreasing my immediate odds for safety is not worth some perceived future gains that I'm not even sure exist.
"Many people who wear helmets can relate their experience of a crash which leads them to believe that a helmet 'saved their life'. This is a very common experience - very much more common, in fact, than the actual number of life-threatening injuries suffered by bare-headed cyclists. Yet there is no evidence that helmets save lives or prevent serious injury at all across cyclists as a whole"
The PDF linked at the bottom is good too, it's written by a guy that runs a cycle helmet testing lab.
It's an in-depth piece and I don't want to do it an injustice by over-summarizing but here's my take: helmets by design and because of basic physical limits on their size are good for when you fall off a bike onto a flat surface at low speed, not for collisions, certainly not getting hit by speeding cars. Therefore they make a lot of sense for children learning to cycle or others prone to falling off, and much less sense for average cyclists.
Well to complete the anecdote, her tire go caught crossing some railroad tracks (she was an experienced cyclist), she fell and hit her head on one of them. Her doctors praised her wearing a helmet, so I'm apt to take their advice over yours.
When trying to decide how a policy will affect a population, you can't reason out from a single anecdote. Remember, the plural of "anecdote" is not "data".
When implementing policy you need to deal with politics. These decisions are not made in a computer on data alone, every bill will hear numerous testimonies and requires the judgment of lawmakers.
What you're proposing is counter-intuitive to most people's everyday experience, ie. wearing protection is safer than not wearing it. Sorry, but if you really want to convince people you are going to need more than data, because the other side will have their own stats - and crying mothers and all that jazz.
Maybe me wearing a helmet increases the perception of danger, but hell, it's dangerous out there. Decreasing my immediate odds for safety is not worth some perceived future gains that I'm not even sure exist.