Here is some observations not based on any facts. I'm sure Cessna made a million of these switches and all their other electrical parts as they keep turning up in every model. Think of the courtesy under-wing light switches from 172, a bit white chunky thing, which are still found in modern Caravans.
Thinking that its easier to recycle the generator or alternator than turning off the entire electrical system with two separate switches . Guessing also that these switches were in 100 series when they still had generators.
So I'm saying its a legacy for parts more than design.
Of course I could be completely wrong
