The problem with helmet laws is like seatbelt laws. Police often go out of their way to enforce them in situations where it just doesn't make any difference. In fact, there are situations where seatbelts may cause more harm than help (whiplash, entrapment, etc).
On a few occasions, I've deemed that the helmet was actually more dangerous to wear than to remove, generally due to overheating in low risk areas.
I would like to see greater helmet use, but would also like to see more people actually out on the bikes.