Well you can't really legislate that people have some common sense, and you can't really legislate against people being stupid in one form or another. But I will state the reason why I wear a helmet while out quadding with the wife and kids on my Kawis
First it sets a good example for my kids. I don't want them thinking "Hey, Dad doesn't wear a helmet so why should I on my quad/bike/etc"
Second is that it doesn't take much for a loaded ATV to go over backwards or on its side on slow technical trail. You can say it won't happen to me, or you can say " where the heck am I?" cause you landed on you noodle or you can say "gurgle gurgle drool gurgle" because you were unfortunate enough to suffer a serious brain injury.
Third reason would be my tax dollars. I wear a seatbelt because it saves lives and prevents more serious injuries, saving our already overloaded health care system money. Not because if I don't I'll get a ticket.
Fourth reason would be it's COOL, ever see the SNELL and DOT approved lids shaped like the WWII German helmets?? Each to their own but I just might get me one!
This all being said, I don't have a problem with what Rugatika and Walleyes said in that it is common sense and depends on the riding you do. When I'm at the farm in SK and head out in the pasture to check cows or shoot gophers or pick berries or what the heck ever, I may not wear one. But I've gotten in the habbit of it and its like a seatbelt for me. I feel naked without one.
So if you're at McLean Creek this weekend and see some guy wearing a full face dirtbiking helmet on a Red Brute Force with a 6 and 4 year old following him doing on 2 little green Kawaskis doing 2 miles an hour on a perfectly flat trail,............. that will be me
PS: as for legislating it, I'm on the fence, if Farmer Joe ( or my Dad for that matter ) in the middle of the prairies is putting across the quarter section to check his cows, honestly why does he need a helmet. But if you're out ridding in the foothills or in the designated off road areas where a trail might get hairy, that's another story.