Probably a bit of both. Having that mechanism is just another point of failure, and seems like it would a pain in the ass to install and test on an assembly line.

And here in Canada it’s required that new vehicles have daytime running lights, ie. lights are on (but at a dimmer setting) whenever the vehicle is running. Because it’s easier to see vehicles with lights on them than a vehicle with no lights in poor weather conditions. So pop-up lights would only make the vehicle look nice when it’s parked, but it wouldn’t look good whenever you’re driving, even in the daytime.