The helmet law in Massachusetts (MGL ch. 85 §11B) only mandates helmets for cyclists age 16 or younger. This applies everywhere bikes can be ridden.
As for whether I would support a law that requires everyone to wear a helmet when riding their bike, the answer is no. After a minor accident in college left me with a concussion and seven staples in the back of my head, I wear a helmet whenever I’m on a bike, without exception. And I think that everyone on a bike should do the same. However, a law mandating bike helmets is not the way to achieve that goal.
When I was a summer police officer on Nantucket many years ago, I was tasked with enforcing the town’s bike helmet law. I quickly realized that hassling tourists about something that didn’t directly endanger anyone but themselves was a waste of time. Like so many issues related to bike safety, the focus should be on education — not legislation (zing!).
Also, I fully support efforts to make it cheaper and easier for everyone to get themselves a helmet. Check out H.E.L.L. — they’re supported entirely by donations and provide a great service.