Motorcyclists are at a much greater risk of injury in a crash due to our being "out there" with no cage around us. So I prefer to not be involved in an accident, rather than to try and lessen the potential harm. I lessen my chances of being in an accident by NOT wearing a helmet. I have much better vision without one and I have much better hearing without one.
I avoided what could have been a major crash on I-75 one year because I saw the idiot out of the corner of my eye. I have no doubt that had I been wearing a full face helmet I would have been seriously injured.
As far as forcing the rescue personnel to see my brains scattered about, what about the doctors who are forced to see lungs rotted by smoking?