Re: good idea to design a passenger plane needing active computer assistance to stay airborne ?
It sounds like you want to avoid Full Authority Digital Engine Control.
On the 737 MAX*, computers control the engine operation. The pilots can start the engine, command thrust, or shutdown. They can see temperatures and shaft speeds, but have no direct control over individual parts. Imagine your car if they took away the manual choke and added electronic ignition.
MCAS isn't required to keep the aircraft in the air. If the pilots are trained on the 737 MAX**, they can fly without it. Hell, it's probably safer with MCAS disabled.
Active yaw damping is another situation where computers "actuate controls without input from the pilot." If that malfunctions, you just get seasick. You don't die. So we'll leave that.
Engines, though. It's hard to stay airborne without engines.
*possibly most other modern airplanes too
**extra training is exactly what airlines did not want