Change control is a major source of issues
A big part of the development process failure may be change management. The failures are still shocking but a little less so if a reasonable safety analysis had been conducted and then changes were made that invalidated that analysis but it was erroneously believed that the changes were not significant.
My expertise is in safety related electronics and software in the medical area and the FDA have research to show that changes to software is a major source of safety incidents.
Now I would say that my understanding of MCAS is that the fundamental flaw is not the software itself but the specification of the software and the sub-system design concept which is inadequate due to a failure to appreciate the severity of a failure of this sub-system. Howeve rthe ide a is teh same change management is a common cause of failures/high risk area in the development of safety related systems.
It still seems like a shocking failure of the development and certification/compliance processes.