A few weeks ago, I was biking somewhere at night, with my front light on and back light flashing, and a motorist was coming the other way. He did not turn down his brights. Blinded, I plowed into a giant pile of leaves.
I'm lucky, because a giant pile of leaves is basically the ideal thing to have in front of you in case you have to plow into something. But it was also completely terrifying, because anything that makes your bicycle stop suddenly is scary. As is not being able to see a damn thing.
Now, I don't drive, but it's my understanding that if you don't turn down your brights when an oncoming car approaches, you are a jackwagon of the first water. And I'm pretty sure that this isn't because of some magical forcefield that automobiles have that makes bright lights a problem. So if it's a safety issue for motorists, why would it not be a safety issue for cyclists?
This has been your Angry-Face Bike Safety Tip of the Week. Or, more properly, your Angry-Face Don't Be a Jackass to Harmless Cyclists You Encounter Tip of the Week.