Accident data  

According to the FAA there are roughly 45,000 flights per day if 5000 of those are helicopter. That would count for roughly 11% of the total flights per day, which is probably on the high side. So your argument about wearing helmets has some validity. But as stated above, you need someplace to put the goggles. In the early years of flying EMS before goggles we wore headsets and much like kids riding in the back of trucks and drinking out of the garden hose. We survived. 

We are living in a time of over regulation and too many lawyers.