I think the key part is “the LEDs could be made dimmer, or the halogens brighter, the manufacturer chose not to”.

It makes sense for plain ol halogens to share the same socket as plain ol LEDs, because they function in the same way and are the same brightness.

But bulbs of different characters probably should have different sockets, so that high-intensity bulbs of any kind (eg xenon, laser, led) cannot be used in a regular lighting fixture without the necessary hardware to make it safe.

But here we have another problem - standardizing car parts is very beneficial to the owner because it makes repairing much easier and cheaper; if every manufacturer uses their own connectors for everything, then vendor lock-in would get that much worse and replacement parts would get that much harder to find and more expensive.
If manufacturer we’re encouraged or forced to use standards, and we’re instead encouraged not to, then they’d all make their own proprietary connectors for everything forcing you to get all maintenance done at official dealership where they can charge extortinat prices.

So it’s kind of a damned if you do, damned if you don’t scenario. I think all we can do is regulate the behavior we want to see, and fine manufacturers, garages, and drivers that violate it.