Car designers also mostly used them since they were forced by regulation to use circular or rectangular lights of a standard size (think of all those 80s cars that look similar in the front). Pop up headlights allowed them to hide them and create cars that looked much different from the rest. I think there is a video from technology connections on the matter.

Edit: I think it is briefly mentioned on this video, although it’s been a while since I watched it: https://youtu.be/c2J91UG6Fn8

Yep. The technology of the time was pretty limiting. We have better tech and could do it better and more reliably but we don't.

Around here new cars have to have the lights on (but on a dimmer setting) whenever they're running. It's easier to see an oncoming car with lights on during the day when it's foggy or rainy. In conditions where lights don't improve the visibility of the road most people don't think to turn them on simply because it'll increase the visibility of their car to others.

So in places where lights are required to be always on, lights like these would only give a sleek look when the car is parked. Also aerodynamics are a consideration, and like you say they tend to break.

Just one of those fun little ideas that didn't work out for a number of reasons.

I remember it well lol. Back in the day, I had a Triumph TR7. I had to disconnect the headlight motors and run with them up, because of 'winking'.

They did have manual controls on pretty much all of them, i think it was more a failure rate thing than a safety thing.