What was wrong with the days when there was only three or four light bulbs and screw threads or bayonet mounts ?
My recollection is that this wasn't some Ford Engineers brain fart. Generally speaking the auto industry is/was under heavy regulatory pressure to improve lighting reliability and durability. I'm sure you have probably seen the old light bulbs quit and require a turn or to remove and replace them to get them lit again. I certainly have.
Proper bulb retention makes sure that critical vehicle lights remain in place and correctly aligned, even under the vibrations experienced during normal vehicle operation (this vibration can't be over estimated). Reliable lighting is directly linked to both visibity to others and visibility for drivers. I think we can all agree that improvements in vehicle lighting systems can lead to reductions in certain types of accidents and even fatalities.
What was wrong with the days when there was only three or four light bulbs and screw threads or bayonet mounts?
Let me count the ways..... But bottom line is that lots of things changed and the old lighting systems not longer met requirements. In a very real way, they had to die so we could live.
How is this an improvement ?
The auto industry adopted spring retention systems for light bulbs primarily to provide a secure, vibration-resistant, yet cost-effective method for holding bulbs in place within vehicle lighting fixtures.
The spring clip or retaining spring secures the bulb against its seat with sufficient force to maintain both alignment and electrical contact, which are both important for both optical performance and safety.
To expand on that a wee bit, the main reasons for this change include:
Vibration resistance - Vehicles experience significant vibrations. Certainly more than a TV or microwave oven. Unfortunately, traditional screw-in bulbs or friction-fit sockets or twist and turn sockets have a long history of loosening over time. As I said before, we have all seen it. Spring retention systems are much better at absorbing and enduring vibrations. This reduces the chance of bulb failure due to both loosening and filament fatigue.
Secure mounting - The spring system helps ensure that the bulb remains properly seated. This helps prevents intermittent electrical contact.
Cost and simplicity - the metal spring designs are relatively low cost to manufacture and assemble in automotive quantities compared to other ways of doing it. I know that sounds self serving for the industry, but it also reduces cost for consumers too.
Ease of maintenance - Spring clips help facilitate relatively quick and tool-free bulb changes. This is important for both regular maintenance and repairs in the field. Yes, it requires relearning what you used to know, but hopefully you will come to appreciate the change in time.
Why do we have to suffer engineers improving things just so they seem important ?
Again, this wasn't just a Ford Engineers attempt at fame. The entire industry is doing this.
I think that urban legend that some engineer is busy making changes for the sake of reaching for fame is over rated. There is an entire chain of command in place to prevent that sort of thing. Usually, the engineer is just doing his job.
That doesn't mean they never make mistakes or that some ideas are not stupid in hindsight. It happens. I've seen it myself. But I think it's the exception, not the rule. In this case, it's an entire industry shift. One that makes sense - at least it does to me.