Perhaps the issue is our relationship with automation that is the problem - on one hand we want automation to reduce the pilot workload yet on the other, we require the pilot to constantly monitor what the automation is doing.
I do a lot of motorway miles and I rely on the cruise control to keep me at a sensible compromise between the speed limit and the point where plod will start to take an interest in me.
Depending on weather conditions and traffic I will spend either 10% or 90% of my time monitoring the cruise control to ensure it keeps me in the right place with reference to the surrounding cars. Sometimes the traffic density requires me to disengage the cruise control completely, sometimes a simple blip on the increase/decrease speed control is required.
There is no doubt that the cruise control can maintain a constant speed far more accurately than I can, but there is equally no doubt that sometimes it is too limited for the constant change in circumstances that motorway driving brings about.
Intelligent autopilot anyone???