It's all about -- as has been referenced here several times already -- the AIM of the light. The light itself, as a safety device or a light to show you the way, cannot be too bright. IF it's properly aimed, and you get cars flashing their brights at you, then you're close to ideal.

Two points:

1. To see (hazards in front of you), and
2. to be seen (so you don't become a hood ornament)!