Certification is a binary process denoting an acceptable level of risk. Safety or risk is inherently not binary but is subject to the exercise of judgment to arrive at a compromise that can be certified. Not sure what the pregnancy argument is about but clearly no system is absolutely safe but when you are pregnant you are absolutely.
MCAS is popularly considered to have introduced an unnecessary level of risk that should not have been certified. It is probable that the aircraft would have been safer without MCAS and the pilots were responsible for potential pitch up conditions due to the new engine locations. The investigation will have to resolve these suppositions and whether there were fundamental irregularities with the design and certification process. Quite rightly the focus must be on whether the design and certification was appropriate. Consideration of pilot performance are of course relevant, but are not the primary cause of the accidents and are not capable of obvious remedial action. There will always be pilots of varying ability. It is far from certain that the situation that they found themselves would have been recoverable by average pilots... more information is required to establish what the pilots actually did at all stages of the flights.
Based on the limited information, it appears to me that MCAS introduced an unacceptable level of risk and those risks were known to Boeing and possibly the FAA. It is not a good situation for public confidence in safety.