For the running subclass of pedestrians, it's a bit more than an annoyance. During my Silicon Valley trips (typically one week a month) I often run on the Steve

For the running subclass of pedestrians, it's a bit more than an annoyance. During my Silicon Valley trips (typically one week a month) I often run on the Stevens Creek trail, early enough that it's pitch black in places. I wear my own headlamp, which I'm careful to keep turned low in both senses. Some of the early Google commuters have their super-bright lights aimed so high that they're right in my face even though my head is even higher than theirs. The resulting blindness might not endanger my life, but it certainly increases the risk of a wrong step leading to a twisted ankle or knee. The best solution safety-wise would be for the path itself to be lit, but of course there are cost and environment issues with that. So we're left with better lamp design. As others have pointed out, multiple LEDs would be better than just one. Reflectors and lenses to keep the light more focused forward and down would be even better. Unfortunately, better lights are likely to cost more, so nobody would buy them. As with the SUV drivers and their super-bright blue/purple lights shining straight into car drivers' faces, danger to others is an externality the purchasers don't care about. People will buy the lights that give them the most lumens on the path/road per dollar, even if half the output is not helping them but is increasing danger for others.