If I were to design a new big widebody I'd bring back the F/E.
In the early 1990s I positioned somewhere in Australia on an Australian Airlines B767. I visited the flight deck to say hello as a fellow pilot and was surprised to find three crew!
The aircraft had been modified to accomodate him with part of the overhead panel relocated to an engineer's panel on the right of the flight deck and also a small screen of some kind (I forget what it was precisely). I stayed for landing and apart from reading the checklists he did little else.
To design an aeroplane for a flight engineer and make it meaningful would be to reduce automatic monitoring and switching, effectively creating work where previously there was none.
I have little doubt in the cowling incident a flight engineer would probably have picked up the omission but I do not think this (preventable) incident warrants bringing back the flight engineer.