There is nothing more annoying than flashing bike lights. There is no need for them and they are in fact more dangerous than they are safe. They distract opposing traffic and are much more likely to cause an accident and all those idiots who use them should be tried for crimes against humanity. Or just shot.
Can you imagine if every motorist in London had their headlights flashing instead of just on? That would be like running for the toilets, in a pitch black disco littered with strobe lights, while trollied on Jägermeister. The chances of you making it to the bog unscathed are slim to none. Nobody does that, so why do cyclists in London do that?
Disco lights blind other cyclists and don't serve any purpose other than making the user feel like they're some sort of all powerful, alien invading force with godly powers.
Eric Scigliano puts it eloquently on his Seattle based Blog, Crosscut:
No one is more vulnerable to that pulsing glare, or more resentful of it, than other cyclists: when blinded, we have a much smaller margin of error than motorists. "Death to strobing headlights!" writes one. "Who the hell needs a strobe on a bike trail? Some day I am going to throw my water bottle at one of those f-ing (flashing) nimrods... The complete lack go regulation on these seizure inducing headlights ... can only end in the blindness of our species or reasonable regulation. I pray for the latter."