I've thought the same thing. Some bikers have lights which flash extremely brightly and aimed at eye-level, probably with the idea that brighter things are harder to miss, but whether I'm a driver or a biker, I hate to be behind them since they are painfully blinding.

I wonder whether the best light is two: one which is always on and one which is flashing. Flashing lights are to get drivers' attention even when it is in peripheral vision, and the steady light is for speed/position estimation.