So is there any point in any kind of helmet at all?
Putting risk compensation aside for a moment. My personal view is that the widespread adoption of bicycle helmets suggests to the general (cycling and non-cycling) public that cycling is a 'dangerous' activity. Well it must be dangerous, why else would they all wear helmets? By wearing a helmet we propagate that myth. Anything which puts people off cycling is a Bad Thing. Every bicycle helmet is an attack on cycling.
Cycling - as we all know from analysing the statistics - is not a dangerous activity in itself. As we know: the health benefits of cycling outweigh the dangers by a factor of twenty to one. Any danger posed to cyclists is delivered by other road users. If we want to remove that danger it seems to me perverse and wholly unfair that the victims of the danger be obliged to 'protect' themselves. It would be like suggesting that people must wear bullet-proof vests because someone is shooting off an AK-47 nearby.
And they are a false sense of security - you only have to look at what is involved in the official test procedures to see that.
I would much rather ride my bicycle in a way which minimises my exposure to danger than wear a lump of foam on my head in the delusion that it will do me any good when I fall.
And as Cunobelin so lucidly illustrates - by any measure, cyclists are way down the list of people who should be wearing head protection.
So, they don't work, they don't deal with the actual danger which would be a better target for our efforts, and even if they did we'd save more injury and deaths by making drunks wear them.
There is a massive industry behind cycle helmets - don't believe the hype.