In reply to many:
Oh christ. The point people have been trying to make is that helmet wearing is no more a logical decision than it is to not climb in the first place.
Everyone saying 'it's stupid to not wear a helmet, I always wear one' could just as easily be saying
'it's stupid to rely on leader placed protection, I only ever climb on bolts',
'it's stupid to climb on loose rock, I only ever climb at stanage'
'it's stupid to do high altitude mountaineering, I only ever go cragging'
'it's stupid to take risks by climbing, I never leave the ground',
'it's stupid to risk food poisoning by eating soft boiled eggs, I only ever eat mine hard boiled'
And all of the emotional blackmail 'how would your loved ones feel etc. etc.' just as equally could apply to support any to the above statements.
Yes, helmets may reduce your level of risk, to a greater or lesser extent depending on the climbing environment. On a loose and serious sea cliff, say, it would tend to provide an increased level of protection than on a heavily overhanging limestone sport route where you have nothing to hit on the way down and very little that is likely to fall on you.
In certain circumstances, where people consider it
relatively safe to do so (remember, if it is complete safety we are after then it's not logical to leave the ground or even go to the crag) then they may decide that unrestricted freedom of movement is more beneficial, and more
enjoyable (and let's remember, we all choose to climb for enjoyment despite the risks involved) than wearing a helmet.
It is no less logical to decide not to wear a helmet than it is to decide to climb in the first place. The decision whether or not to wear one is made based on weighing the potential risk of the situation, the consequences if something were to go wrong, and to what extent a helmet might mitigate those consequences. Hence helmet wearing is more prevalent on a Yosemite big wall or at Swanage than it is at a Spanish sport crag. It is a personal decision and what is appropriate for some people is not necessarily appropriate for others.
So please can people stop with the excessively alarmist and emotive ranting (Tim Chappell, I'm looking at you) and go back to respecting everyone's responsibility to choose the level of risk appropriate to them based on the specific circumstances, as we do with all other aspects of climbing.