Prompted by a previous post, what do people think about skiing helmets?

On my last couple of trips to N America helmet use by adults seems to be
approaching 30-50% (very rough guess). When I was in France a couple of
weeks ago it was very close to zero.

Personally, I'm a convert, but a trip to Jackson Hole is very pursuasive
(very steep, lots of tight trees, scary cliffs etc). I guess it still
very much a matter of debate and I am not in favour of making them
mandatory but I'd be interested to hear what anyone else thinks.

On the plus side:
They probably reduce the chance of serious head injury in an accident.
(although I know of no proof)

On the down side:
Can be uncomfortable (mine current one isn't, the first one I bought was
a real pain, literally).
May encourage a wearer to take more risks (I doubt this, but I've heard
it said).
Too warm in spring/summer.

Thoughts?

Steve