I'm also persuaded by the "expert cyclists" - those that do commute regularly or cycle to a high standard - the majority of them wear helmets.
That'd be me then. 28 miles a day AND I wear a helmet. So here's my "persuasion"...
The reason I do it is two fold.
Firstly it's somewhere to fit a camera.
Secondly if I'm unlucky enough to be involved in an accident I don't want me (or my kids) to be fighting an insurance company that'll use any tactic to wiggle out of paying.
I'm under no illusions about the benefits of a polystyrene hat. In a collision with another vehicle they're all but useless. Indeed the real problem with them is how much use (or liability) they are depends on the type of accident you have.
So for example:
If I was to fall off my bicycle and hit my head on the edge of a kerb - I'd want to be wearing one.
If on the other hand I'm whizzing down a road and 'lose' the bike I'd rather not, in that instance falling from under 5 feet will see my head hit (if it did) quite lightly - same as falling over whilst stood up, but the 20mph plus forward velocity will try to impart spin to my head. Without the helmet all that would happen is the skin would tear, with the helmet the helmet will 'bite' into the tarmac and start to rotate taking my well strapped head with it. This results in rotational brain injury - probably one of the more common types and wholly unavoidable and indeed more likely with helmets - particularly when taking into account the extra radius and mass.
In summary. What sort of accident are you going to have? I'd suggest the type is based on how and where you ride, therefore to some extent you can bias the chance of one particular type of accident over another. Given that only I know this, then shouldn't I be the one to decide whether a helmet is a good choice or not?
I should point out I don't wear a helmet for local use, neither would I bother if it became illegal not to. I'm old enough not to care, fast enough not to get caught and believe that since the roads are under policed anyway it'll make no difference. (If we can't catch speeding, phone using, infrastructure ignoring drivers, why should we suddenly be able to catch a load of bicycles?)