For many years I managed a lot of programmers and I’m a programmer myself. All this automation in the aircraft is run by sensors feeding data to programs like the ones that my folks wrote. I also took software engineering graduate courses in software safety. Software is great for relieving a pilot of complex or tedious tasks but it remains a tool for the pilot. There is no way for software to react to every possible emergency situation. If a single pilot gets ill or incapacitated (or dies) in flight, then another pilot is needed. Having two sets of eyes and brains to figure out aircraft system problems is better than one set. In addition to the software there’s a network of sensors that feed data to the aircraft computers. These sensors can malfunction and feed bad data to the computers (737 MAX). Pilots are mobile troubleshooters in that situation - something aircraft hardware and software are not. Someday the progress in AI might make up the difference but that’s not today. We all know that having a single point of failure in an aircraft is not a good thing. The same goes for a single pilot in an airliner.