It should be noted that the manufacturers--all of them, US domestic included--were dragged kicking and screaming into compliance with many regulations made in the name of safety or emissions or both starting many years ago. Laminated windscreens, safety glass, etc. predated emission controls and were not universal on the world's cars when they were mandated here. Having been in a horrific crash in a 1968 MGC in 1975, I'm sure glad it had a laminated windscreen. Of course, if it had not, you would not be reading this post as I probably would not have survived. Lucky me and you!
There was a period of time when the manufacturers struggled to keep up, most likely because they really did not want to do what they were forced to do. You can call that a lack of investment or engineering, or blame it on the [US] Feds; doesn't matter.
But look today at the safety in cars, and the fantastic engineering accomplishments that have resulted. Advanced crush and crumple zones; airbags of many sizes, shapes and locations; integrated lights (as opposed to stick ons as noted in this thread); all have contributed to a safer driving experience in modern cars from all manufacturers. Engine emissions are wildly lower than the 1960's.
Dealing with the vagaries of the market is daunting for the manufacturers--trust me, I'm in the thick of it here. When the first Ford we bought here was offered with airbags in 1987 (
optional, due to federal mandate) Ford couldn't sell them at all--and in fact at one point the airbag Tempo was lower in cost than the non-airbag version just to dump them! Nobody wanted them, and they certainly did not want to pay "extra" for them.
Today, of course, USA federal mandate aside, a manufacturer could not sell a mainstream product without
multiple airbags. I like Ulf's comment about how little Mercedes actually had to change things--they have always been on a path of safety.
Now, whether or not to add/remove side markers or reflectors on your Pagoda, or bumper overriders, is purely a matter of personal taste. And, let us not blame the USA for every detail change. Many countries have their own mandated regulations for cars. Think the Italian side markers, or that French contraption on David Pease's car that shuts off the car if it rolls, or rear fog lamps...even today there are plenty of regulations around the world that manufacturers must deal with.