There were different types of relays manufactured, for example, for the telecom industry. Very high precision and low failure rates required.

This is compared to a pinball machine or other amusement device, where the tolerances can be higher. Gottlieb used a higher precision type of relay, but it doesn't make the machines easier to work on.

If the technology continued to advance, you would likely see a shrinking of the switch contacts and blades, making everything higher precision, but in reality just allowing more switches to exist in the space available. But you can only shrink them so far before components no longer work.

Space is really the issue in amusement devices. You have a fixed area in which to put stepper units, motors, and relays. The Bally bingos utilized the space within the head very well, but they did so by bumping out the dimensions to fit multiple very large units.

Steppers could also be reduced in size, but the beauty of most steppers is their reliability. When you make something smaller, you don't necessarily make it more reliable (the double-edged sword of the high-precision relays mentioned above - you need special equipment to measure the tolerances).

Of course, you can see differences in manufacture just between the 3 major amusement device manufacturers. Whether they built the connectors, fuse blocks, steppers, switches, etc. in house or farmed them out to a 3rd party - each arrived at the destination in a slightly different way.

Worth noting that over the years there were changes to each manufacturer's approach to suit costs or reliability or ?

Without computers, though, I know I would be out of a job. Maybe I'd be turning a wrench instead.

Ramps, magnets and multi-levels were all used in the 1930s and 1940s. Necessity is the mother of invention and I'm sure the features would come back into style just as they did in the 80s.