Partially to blame on the low adoption of helmets is the difficulty choosing and obtaining one in many parts or the world. At EUR 2,000 or more a shot you want to try for size and comfort. In our part of the world, I am not aware of a single place where you can do that.
This year I was in the market for a MSA350 helmet (as it was highly recommended by some of the Ppruners here). As I was travelling to Europe, I wrote to MSA Europe headoffice in Berlin, no response. Later I was going to the US. I contacted MSA US, and was told that the MSA350 helicopter helmet was only sold by MSA Singapore and was not available in the States.