Honestly, I kinda wish it would come back. Forcing all manufacturers to use the same part for headlights had a singluar massive advatage that is gone now:

You could walk into any parts store and they always had the headlight you needed in stock, on the shelf.

Prices could be lowered dramatically as well because they were produced in such massive quantities. Sure, bulbs are more or less "cheap" now, but imagine being able to walk into any parts store and buy a pair of new LED headlights for your car for just $8 USD. You can't do that now (at least not here in California, the cheapest LED pair for lows only is like $30 at AutoZone), but you could if manufacturers had to use the same light module. And this same process could apply to any variety of other automotive parts.

Despite the limitation of the law requiring certain modules, cars back then had their own unique styling. Just looking at them, you knew exactly what make and model it was, and sometimes even the exact year. Nowadays, with no such limitation, I find cars to be more or less the same boring blobs driving down the road with a similar silhouette and in a paint variety of black, white, or grey/silver. I have to really pay attention to the taillights if I want to identify the make/model/year.