All the points so far have been well made. The only thing I can add to this discussion is that the pilots in today's jets are really flight engineers in themselves. Computers have played musical chairs in the cockpit. The pilot flies, the co-pilot monitors, and the FE gets the pink slip. The last time the music stopped, it was the navigator that got left without a seat.
In today's fourth generation jets, the pilots spend almost all of their time monitoring the aircraft, not flying per se. So there is no reason really to have a FE when you already have another flight engineer in the cockpit already. On autopilot, you have two FEs in the cockpit. Generally, one pilot is a FE that flies, while the other pilot is a FE that monitors and communicates.
Which brings up the issue of the navigator. Long before most of you guys were born, there were four bodies in the cockpit, two pilots to fly,.one engineer to handle the engines, and one guy to read navigation charts and talk on the radio. Well, we got rid of that last guy about 40 years ago and nobody misses him today. Flight engineers have gone the same route.
We could eliminate pilots, too, from the loop, and since most accidents are caused by pilot error, we would save a lot of lives and be better off for it. The only reason for not evolving to that stage is that the flying public would be hesitant to board a plane without pilots. If Airline A flew aircraft without pilots, while Airline B flew aircraft with pilots, I don't have to tell you which plane would fill up first.
So, getting rid of the navigator, and getting rid of the flight engineer, was all about saving money. But keeping the pilots in the cockpit is all about saving face.
An optimist robs himself of the joy of being pleasantly surprised