In reply to UKC Articles:
I think it's important to recognise that a helmet won't protect you completely, whether you're hit by a partner or fall rocking, or fall yourself. But, the head a) has your brain in it and b) is relatively easy to protect. It'd be great to be fully protected from a fall - but, body armour probably wouldn't work and would be pretty cumbersome... So, if you're looking to protect yourself from risk, a helmet seems a good place to start.
On this note: I imagine that one reason trad and winter climbers wear helmets more often is that a big part of these disciplines is thinking about how to protect the ascent. You'd have to be mad to go winter climbing without a helmet, especially in these days of lean conditions meaning you've 5 parties ahead of you and 5 behind, up the only frozen gully around. Heading up an "easy" grade II gully on Brown Cove Crags this winter, my partner, leading above me, shouted down "rock" to me. No one had shouted it to him, but someone above had knocked a skull sized lump of rhyolite off and it was ricocheting down the chute like a pinball. I shouted "rock" and watched another leader below me look up from where he was arranging a belay, pull a terrified expression, and then turn his shoulder toward the expected impact. Somehow it bounced centimetres under his face, between his body and the banked snow.
Anyway - a second thing: in a bored moment, I've watched a couple of those "Whippers of 2016" video compilations people post on Youtube. And one of the arresting things you notice as you watch 50 people whip is how many of them fall over backwards - not only because of tripping over the rope, but also because they're on slabby ground, or just because their hands popped off with force. Given how likely an inversion seems, protecting the head, neck and back is a real concern. The only time I've had to catch a whipper, it was climbing a slab. The leader fell maybe 8m and ended up suspended horizontally with his back and head about a foot off a ledge.
Finally, I reckon Andy Cave's onto something: when people are introduced to the sport, we should set a good example and get them putting helmets on. I've always worn a helmet when climbing outside (I often even wear it when bouldering and usually when soloing), and it never feels "odd" to have it on because I've always worn a helmet since I was first introduced to the sport by friends who lent me gear, including harness and helmet. Conversely, I grew up cycling helmet-less and, although I've been shocked recently by personal near misses and hearing of cyclist deaths at the hands of careless drivers, I still don't wear a helmet (I probably should... I probably won't). Make it the norm when introducing new people to the sport, and it'll become the norm.