I haven't been "blinded" by a Merc, Beemer, or Acura with xenon lights - the color is different and they seem more dazzling (possibly because the light is a small point source?) but I don't find them dangerous. I have seen dangerously bright glaring xenon lights on Civics and Mazdas - most likely the non-DOT HID "H4" lamps that the rice rocket crowd love since these cars do not come with such lights... I haven't seen any DOT aftermarket xenon/HID lamp kits.
The H4 lamps are in a bit of legal limbo. A decent brand H4 system will have a "legal" light pattern, but DOT regulations are a bit strange. As I read the regulations, you can't install a better light than the vehicle came with... so if a sealed beam was stock, an H4 is not allowed. There may be some slack when the headlight assembly as a whole is identical (except for the removable lamp) but that's a grey area as I read it... and probably it isn't allowable. So apparently headlight units that meet DOT luminance standards (bright enough where you need light, not too bright where it shines at oncoming drivers) can't be installed on vehicles with pitiably dim stock headlights.
This restrictive regulation makes HID H4 conversions totally unacceptable - good in my view as they are the worst for blinding oncoming drivers/riders - but catches reasonable unpgrades using acceptable luminaires as well. The regulations should probably be rewritten so that the actual light pattern is all that matters: if a headlight gives an OK light when installed on my bike then I should be able to use it. Unless that happens, almost all aftermarket lights will be "offroad only" and we have no way of really knowing whether what is available is a good headlight or a road hazard.
Be careful with ebay stuff. I started to install a set of H4 headlights (from ebay) on a friend's car and noticed the lenses looked funny. Experimentation soon showed they were for some drive-on-the-left country - the light pattern was flat to the right and way up from centre to the left... perfect for blinding an oncoming driver and exactly opposite to the pattern I was used to with locally purchased units.