In places like New York, where their Citi Bike scheme has had huge success without helmets (23 million miles of riding, no deaths), utility cycling (commuting) has been made safe through a huge investment in the segregation of cycles from cars and pedestrians. The health benefits to the city are huge (as well as reducing congestion) and you get people of all ages cycling now.
In Australia where helmets are a legal requirement, city cycle schemes are failing, but this may also be to do with a lack in building out segregated cycle infrastructure as part of these schemes. It is still a mainly hardcore, male activity there.
The point is, helmets and cycling create flame wars with anecdotal evidence in favour "how it saved my life" and the response being that the health benefits to society of cycling far out weigh the risks of not wearing one (i.e. It's calculated in the UK, that a helmet law would kill 235 people per year more through obesity related deaths).
When I trundle to the shops or pop into town I wear a cap (being bald brings it's own problems), but should I go out on a club ride or go off-roading I wear a helmet as the risk of falling off is higher. I also wear one when I'm out after dark.
Wear one if you want, don't wear one. Just make sure you are out there riding. The health risks far outweigh the perceived risk of falling off your bike.
The real problem isn't helmets, it's the lack of segregating cycles from pedestrians and motorised vehicles. Making people feel safe cycling to and from shops, homes, schools and their place of work.