This is no real poke at anyone individual, but over recent years I've noticed two trends:
1) for cycle lights to get super, super bright and
2) for cyclists to attach said type of light to their helmet.
When I ride in and around other traffic I tend to use the middle or low settings of my Exposure lights. 200-800 lumens is just overkill. There is usually street lighting to aid me and I will tend to run a second front and rear set up for being seen-by. The problem with these expensive and super bright lights is how they usually have little side visibility, you're relying on the road surface ahead being illuminated and acting as a bicycle-beacon.
However, transplant said light to a helmet as many riders are now doing and we create a host of problems. Firstly, the light is not going to be in one fixed position, we move our heads constantly to look around us. Or at least we should... Secondly, by doing so we end up pointing said light at the people we would normally wish to establish some form of eye contact with.
A couple of cases in point that I experienced recently were when riding uphill and giving the friendly roadie-nod to another rider. Said rider responded but in doing so flashed me in the eyes with what I can only imagine was about 50 lumens of very focused intensity. I saw stars for about 5 minutes after and had to stop riding. Another time I arrived at work, walked up to the sheffield stands to lock the bicycle and turned to say hello to another regular rider I often see. She, too, turned and said hello, and blinded me with her helmet-light. It was so bright it actually hurt my eyes, having arrived in near darkness.
Are people really that ambivalent towards others, that they would rather blind someone temporarily? I do wonder if this is the cycling equivalent of a cry for help, or rather a cry for being bloody noticed? A "please god, don't drive into me!!"
What can we do differently? I got hold of several rolls of 3M scotchlite tape for about £3 a roll (in red, amber and white), I also have a sheet of the same stuff in "black". I cut strips and placed them all over the bike, and little strips and blocks to stick to the cycle helmet. I think cyclists should also think carefully before wasting batteries on lights that are over 30 lumens for a helmet. And make sure you try it out! Stand in front of the mirror - do you go blind? Get a mate to wear one and look over at you.
Anything but putting 200 lumens of blinding death into the faces of others.