I definitely gave hardening and redundancy some thought when designing. Just because the originals didn't have it doesn't mean it wouldn't be a nice thing to add. So I think it's a fair question to ask. But I decided it was mostly impractical for my design goals and price point.
My experience with cars is not very deep but I did hear a lot about redundancy, isolated systems, real time requirements and automotive grade components.
Also I would say that controlling the ignition is very critical to a car.
Those are all important, but modern improvements. In the 1980's electronic management of engine systems was still very new to the scene and so most of the systems are still pretty basic.
> Also I would say that controlling the ignition is very critical to a car.