So '38, you're hinting we shouldn't discuss it in case you get an "Law of Unintended Consequences" result that you don't agree with? That's even more anti-libertarian than mandating a full-face helmet
I'd never want o/f helmets banned in the same way I'd never want HANS mandatory - the chance to make my own grown up decision based on my own personal risk assessment.
Talking of FS1Es, another nail in the o/f coffin was when my mate came off his and scraped his visor along the road. Wrecked the front of his helmet, but at least his face was no more ugly than before he came off!
On the other side of the argument, a customer came in here recently and ordered an o/f because he'd been told he wouldn't have sufficient peripheral vision in his closed cockpit car to see the cars lapping him otherwise.
We're getting the same discussion about compulsion in cycling at the moment. I wouldn't dream of riding my racer without a helmet, but wouldn't wear it on my MTB going round the village. Risk assessment again.