Discouraged?
There have been some studies that correlate higher levels of head injuries with mandatory helmet laws. The thesis was that wearing a helmet induces more reckless cycling (higher speeds, etc) due to feeling safer. I don't remember seeing any good follow-ups studies either way and don't necessarily agree with the study.
Personally my wife can't find a helmet that fits, Asians have rounder heads and north American helmet manufacturers are oblivious. As a result we never cycle.