Why would I shine my light directly at motorists or in their eyes? The light is mounted right side, slightly below the fork crown and aimed to project the hotspot ~75 meters ahead. From the front it appears visually similar to a LED or HiD car headlight. My helmet light projects about half as far and almost never ends up illuminating the passenger compartment of passing or oncoming cars. If it does it's incidental, same as HiD lights cresting a rise before the auto-leveling feature activates.
I've ridden around 150 hours per year at night, the past 7 years, and the only feedback I've ever received has been non-verbal (increased passing distance, decreased speed), or positive - "You're lights are great I saw you from way far away" & "I thought you were a motorcycle haha". In my experience, motorist anger is almost always directed at cyclists because of the activity itself, not the behavior of the participant. Fully half my negative interactions (all during daylight with no lights on) last year were unprovoked verbal assaults from motorists directed at me while riding along a separate bikeway.
As I said:
A very bright helmet mounted light has done more to increase passing space and decrease passing speed than anything else, when riding at night.
But as noted above, individual experience varies so greatly, mainly because the vast majority of cyclists night ride in limited circumstances. Stay bright, stay safe.