Originally Posted by Bluish Green

I think the idea of shining a light on the rider's front has some merit, for at least one specific case (if not more) - for night riding when you are on the more major street with no STOP signs, and a motorist pulls up to a STOP sign on the minor street to your right and is considering pulling out. If it is just you, and there are no cars on your street, he has to see you by just your lights, because his headlights are pointing straight ahead across your road, not toward you. Retroreflective gear on you and the bike won't help much in that case because retroreflective gear reflects straight back at the light source, but his lights are not shining on you. I had a guy pull out in such a situation one night, and if I hadn't been wary and ready to brake, it could have been a crash. Yes, motorists should see you by just your lights (if any), but motorists make mistakes, and anything we can do to cut down on their mistakes is potentially helpful.