355 console switch disassembly and bulb change

Considering the car's age, these cars were probably in the transition phase from incandescents to LEDs. Perhaps they weren't so cheap back in those days. Also, as you can see, older LEDs require resistors (otherwise they will blow with 12V applied to them), so there is a space and manufacturing complication consideration. There were no plug-in, 12v-compatible LEDs in those days, so, for simplicity, they stuck to incandescents, especially in the instrument binnacle.

LEDs will normally outlive incandescents, but they are not always 100% reliable over the life of the car. I'd rather change a non-polarity sensitive bulb than get out a soldering iron in a confined space.

Hope this makes sense
Cheers