Around here in Santa Cruz, a town known for biking -- many local builders, a couple of clubs, and a very forceful pro-bike lobby -- we still don't have the infrastructure that places like Portland or Amsterdam have. In fact, the roads are pretty much crap in most places. So you have to be careful. One recent solo accident involved a young adult who was biking at night on a dark road (dumb) but also not wearing a helmet. He crashed. Currently he is in critical condition. Pretty sure a helmet (and a light) would have helped him out.
The story -- http://www.santacruzsentinel.com/localnews/ci_21655013/santa...
Personally, I've had some spills while mountain biking where a helmet has come in pretty darn handy.
I don't ride much, but one time I was out is the rain and had to swerve on a intersection that happened to be made of cobblestone, and ended up going down hard on the slick stone. Had I not been wearing a helmet, I would have had a severe head trauma.
That type of accident is pretty common, and wearing the helmet avoids lots of needless suffering.
Actually: http://www.active.com/cycling/Articles/Bike_helmet_crushed__...
But, in general your point is correct. There are some dramatic examples where a bike helmet saved someones life, but statically it is unlikely.
Lots of statistics thrown around here, and my anecdotes are not statistics, but they are a heck of a lot closer to actionable information that hot air. As for me, I don't regard a helmet as making bicycling seem dangerous, any more than wearing a raincoat makes walking outside seem dangerous. Its just part of my equipment, like the water bottle.
I think helmets are associated with bikes, because before we used bikes to commute, which involves simply riding about town, we used bikes to rip through the woods inches away from trees and sharp rocks, or jumped them off of mounds of dirt, or flung road bikes down mountain roads at 50per. (at least those three seem to sum up my first 23 years of existence) I live in DC, got old, but still NEVER commute with a helmet, and feel perfectly safe all the time. In fact, tons more safe than when I try to get a training ride in. (for which I wear a helmet)