It all comes down to risk assessment at an individual and situational level, imho. When I cycle around home, to a neighbor or whatever, at walking or jogging speed, I sometimes don't wear a helmet at all. When I commute at 25-28 mph, the potential outcome of a crash is something else. And it surprises me that there still seems to be essentially no helmets with chin guard on the market that are not aimed very clearly, designwise, towards downhill/offroad.