You're right that we can't rule out complacency and human error. And we have internal reviews precisely to account for complacency. Again, I'm intimately familiar with both the safety culture and people involved, this is an unusual and recent development. But I suppose asking you to take my word for it might strain credulity. That is what it is.
I'd be inclined to agree with you more if it weren't for how widespread the smaller issues are. The general trend, among the old and young, is less actual knowledge of the job and more reliance on quick access to information that often isn't applied properly in context. It existed before AI, and has gotten worse with it's introduction. Something about instant access to information seems to harm retention and application of that info. Pretty obvious trend for me, as part of my job is to ensure it's retained and applied properly.
Those procedures built around autopilot, along with other issues of flying more complicated modern aircraft, were dealt with by controlling how information flowed, how it was communicated, and the weight of authority it was given, often with human processes like Crew Resource Management. As I've said, the presentation of information absolutely changes how people understand and apply it. CRM helps because it prompts people to present information to each other in a way that facilitates better decision making and delegation in a crisis.
But autopilot has always been beneficial, right from the start it was obvious. It reduces pilot fatigue on long-haul flights and helps keep air traffic in the right place. Pilot complacency was never really a worry, but malfunctions were.
In the end, it's not that it can't be done. We could adjust our processes to include LLMs simply because people think they're neat. It's just that there's no compelling evidence that its better for distributing information, developing procedures, or teaching people how not to die.