It also reminded me of my biking days some many years ago when we all started putting our headlights on in the daytime. I then attended a police “ride to arrive course” and the advice was not to do that after all, as it impairs judgement of speed & distance by anyone seeing you coming. That seems to be backed up in the above article. When we see a bright light, we automatically close down the iris and in turn alter our perspective of the approaching vehicle.
So maybe bright ain’t always right??
I can see (no pun intended!) that judgement of speed & distance of other vehicles would be affected if you were dazzled by bright lights.
It is also difficult to judge speed and distance of other vehicles at night where there aren't any streetlights because you can only see the lights and no background of scenery or buildings to use as reference points for how fast the lights are traveling. But then again you wouldnt drive without lights in the dark even if legal to do so.
So whilst I would agree that having lights on, particularly on a motorbike isnt always
beneficial, for most weather and light conditions I would say it is.
Police motorcyclists are different in being very visible because they have white fairings, helmets and Hi Viz decals so maybe that is better in the daytime than having lights on?