LED headlights have been in the assessment and approval process of the D.O.T for some time now. If they’re not already legal, they soon will be. But they’ll still be put behind polycarbonate lighting units. The plastic modules allow design freedom and the technology to mold them has progressed to where they are less expensive to the manufacturer than the old way.
I agree with you on the superiority of sealed beam lighting, and in that I don’t believe the average person realizes how much light is lost when the fogging develops. It’s exactly like cataracts for your headlights. I also agree that the restoration kits can only do so much. I personally prefer using regular polishing compound (I’ve tried both) using a wet sponge on a variable speed drill.
It seems strange that headlights started out as bulbs behind glass lenses, progressed to seal beam lights that incorporated both the bulbs and the lenses as one, and are now back to bulbs behind lenses. Only now the lenses are plastic.