I enjoyed reading your adventures. I think I can offer some opinion on the questions you have mentioned.

Every instance of trouble you mention has been caused by the corrosion or oxide buildup on electrical contacts, except the faded high beam filter which is a property of the blue dye compared to the some of the others. The more your car is kept from condensing humidity or kept free of windshield and firewall leaks, the more like a new car it will act with respect to lousy connections. I've seen some of the soggy interiors from up there.

So I want to remove your suspicion that this unreliability factor was somehow added by manufacturing process as a change from earlier builds. There is a certain truth to the increase in maintenance with complexity, just in presenting more features and accessories makes your refrigerator a serious maintenance hog compared with the one you owned in the 60's. But the changes from 87 to 92 don't add up to ice on the door.

Regarding the blue filter with the clear area in the middle - I made lemonade out of that lemon by understanding no oncoming driver would be blinded due to my forgetfulness.

I think you truly love these cars, but don't care much for design engineers.