Michael,
I don't understand how the *intensity* of the light source would cause a dazzle problem - surely it's to do with the alignment? With due respect to any other posters, the type of person who would normally fit uprated bulbs may not be so careful about making sure their headlamp alignment is correct.
My daily commute is a 28 mile round trip. I work shifts, so at least one trip a day is after dark. I never get oncoming vehicles flashing headlights at me, neither do the drivers of vehicles I follow cover their interior mirrors. The three vehicles on which I have used 80/100 Watt bulbs have had a total of six MOT's without comment of lighting problems so my assumption must be that I am not causing dazzle to others.
I should also mention that a number of vehicle which have 55/60 Watt bulbs in the *cooking* version have 80/100 Watt bulbs specified for the performance derivatives. This can be verified from the listings in Halfords ect.
As someone else in this thread mentioned, the biggest annoyance to me on lighting is caused by those who use fog lights indiscriminately. I have mentioned this to a number of people at work, and not one of them understood the laws on this.
With regard to your final comment, my driving experience dates back to 1962 so comparing then to now I certainly don't feel alone on the road ;-)
Chris.