The new headlights on most of the new vehicles are a mixture of several types of lights depending on the vehicle make and model and also aftermarket lamps available. Here is a link to an article about some of them. Just click on the blue text for the article/link. You are not alone in finding that so many are extra bright and then some trucks are higher up and put the lights right in your eyes so it seems. Used to be you could easily tell if an oncoming vehicle most likely had it's bright lights on but today some of those regular lights out there are seemingly as bright as the bright lights used to be.
As for the legality of driving with your bright lights on I don't know if there is a defined law but most likely there is if an officer wants to enforce it and it can be proven. Also there are these LED lights that some trucks mount on their trucks that I know most law officers would take exception to if they were driving with them on. Most drivers I would hope would be courteous and not purposely put their lights on and would dim them if someone indicated that they were bothered by them.