For me, helmet use has always been about choice, risk assessment and informed decision making.
If I were ever to cycle in a large group of sweaty men, all hell-bent on getting over the line first (and all the argy-bargy that entails), a helmet would be worn.
If I spawned an urge to throw myself down an alpine run with total disregard for my safety just to cover a set distance before somone else, a helmet would be worn.
If I got an urge to throw myself repeatedly off a man-made ramp and do 'sick' tricks on a child's bike (whilst displaying my Y fronts for all and sundry), a helmet would be worn.
If I were hell bent on riding to work head-down, as fast as my lungs and legs would let me, and have a reduced abitlity (or awareness) to react to constantly changing traffic situations around me, a helmet would be worn.
If I were to ride at a reasonable pace (sustainable all day), take care on roads and watch out for others, cover my brakes on downhills and reduce speed in the wet, be able to take in the environment around me (birds singing, workmen whistling) then the LAST thing I want to do is encase my head in a lump of polystyrene (recently recycled from plasma TV packaging).
When I ride I always give myself an 'out' - so when a situation arises I have somewhere to go. I use a mirror, so am aware of traffic coming behind from a good way off. I use good quality lights to make myself visible, and I ride defensively - just because I have priority, and have lights does not mean that car pulling out on the left has seen me. Make eye contact, and if in doubt deploy anchors and steer away. Being in a hospital bed and being in the right doesn't seem like reasonable logic to me.
The few near-miss incidents I have had on the road would not have been helped by me wearing a helmet. A car hitting me head-on at 60 is hardly likely to result in me dusting myself down (from all the polystyrene chippings?) and singing the praises of the now tattered helmet.
I am a rural recreational/touring/commuting cyclist, and will not be moulded into a nanny-state helmet-wearing clone.
Sorry.