toysoldier said:What's wrong with sealed beams?.
I believe that the whole thing got going when it became "cool" for auto designers to incorporate the "plastic covers" into the overall design of the vehicle body. The complex compound-curved shapes are now easily developed with computer drafting/modeling and the molding process is likewise much more practical in this regard.
Not having to design/manufacture a headlight "bulb" tough enough to survive weather and other stuff allowed the manufacturers to develop the new bulbs whose only function is to produce light. The "brighter is better" syndrome followed on immediately, and here we are. Now all bulbs can be of an essentially identical envelope and work in all vehicles in conjunction with standardized headlight "buckets".
Just one thing after another. Better? I dunno. I find a lot of 'em irritatingly bright.
JMHO
:)