Well... my helmet stopped nasty gravel rash - not nice on a thigh, but on a non fleshy part like a head....ouch.
I really don't care if you do or don't wear a helmet. For me, and I've said this loads, it helps with sweat control......I ride with a scull cap under it, that soaks up the sweat, the vent's evaporate it - I can climb in the height of summer without sweat stinging my eyes or dripping onto my glasses. In winter it's a windproof scull cap. Prior to 'good' helmets/none, I'd wear a sweat band or cap - they just couldn't cope with the sweat.
I buy the 'more expensive ones' because of the venting - it suits me...
I think it sets a good example to my kids - my son rides like a looney - he's only just 8 but has been clocked doing nearly 30 mph down the slight hill at home.....I've fitted a computer to his bike, and it's calibrated right. He has come off, and on at least a couple of occasions has smacked the curb (low speed) with his head. One impact wrote his helmet off..... saves me a trip to casualty.
TBH I think they look stupid, 'mushroom head' etc. etc. and I take mine off as soon as I get off a bike - you won't catch me walking round with one on....!
If pootling to a local shop, I don't wear a helmet cos I'm in civvies......but if out and meaning 'business' - i.e. lycra lout ......I do..... So shoot me !!!