Not only are they not mandatory but I seem to remember reading that the factory aren’t allowed to install them on later cars, so they fitted them (when the customer ordered them) but the dealer had to connect the wiring as part of the p.d.i. to get around the new regs.
Personally I like them and think they add to the period look of the car, but that’s the great thing about Mogs, we can tailor them to our own taste.
Yes that’s my understanding and I agree with your comments
