I think it’s not so much the reduced redundancy, although that plays a part, it’s the human interaction with two or more crew members bouncing ideas off each other, generating solutions and monitoring the results. You read about pilot error in accident reports but you don’t read about how good CRM stopped an accident chain before it had a chance to develop.
The automation will have to become better, as we are at the unfortunate time where it’s reliable up to the point where things get really bad, then it dumps the whole mess on the (single) pilot. Much in the way of self-driving vehicles in their current state of evolution. If the sole pilot who is awake is in the toilet when something bad happens (there was an opportunity for a joke there but I resisted it), then the aircraft must be able to cope.
If a non-pilot goes flying in a light aircraft with a qualified pilot, they have to assume the chances of survival are not good if that pilot becomes incapacitated, but do it anyway for fun. Will several hundred commercial travellers see it in the same light?