I would bet that the average wearer of these helmets has little understand or idea of what they may represent to others.

My biggest concern is their relative lack of protection. While they may be better than nothing (and that may be debatable for many types of accidents, if you're going to wear a helmet, why not wear one that maximizes your chances of survival in all types of accidents.

OTOH, I was shocked to see this article today, which indicates that motorcycle fatalities are up and the shocking part is that it's in part due to states repealing compulsory motorcycle helmet laws. Helmet law repeals raising motorcycle deaths - Bottom Line

And since we're talking Germany, don't get me wrong, I'm no helmet nazi, but those who "choose" not to wear helmets often cause a serious drain on society when they don't die instantly from their injuries. Often care for them runs well past their insurance limits (when they have insurance) and that increases costs for everyone else.