It's safer to have a new airplane design behave like the old one. There have been many crashes due a pilot being stressed and automatically doing something that would have been right on a previous airplane he was familiar with, but which was wrong for the current airplane he is flying.
All jet airliners are aerodynamically unstable and use active controls to "paper over" that. There is nothing inherently wrong with doing that.
The MCAS problem was not due to its purpose. The problem was the software for it had too much authority, and did not shut off when the pilot countermanded it. A worse problem was the pilots did not follow emergency procedures for runaway trim.
For reference, the emergency procedures are:
1. restore normal trim with the electric trim switches (which overrides MCAS)
All jet airliners are aerodynamically unstable and use active controls to "paper over" that. There is nothing inherently wrong with doing that.
The MCAS problem was not due to its purpose. The problem was the software for it had too much authority, and did not shut off when the pilot countermanded it. A worse problem was the pilots did not follow emergency procedures for runaway trim.
For reference, the emergency procedures are:
1. restore normal trim with the electric trim switches (which overrides MCAS)
2. turn off the trim via a switch on the console