FD
Interesting thought, but consider, amongst others, the 74 Classic into KL - the 'third pair of eyes' contribution to the event was "Oh S..T", one second before they all died in yet another CFIT.
If you want a REAL accident precluder, introduce an Aircraft Commander, on the flight deck,not physically involved in flying the aircraft and having ultimate authority in respect of aircraft manoeuvring. There's no way someone in that position is going to allow his crew to put him in jeopardy!!
It isn't going to happen (and not just due to financial constraints) but, otherwise, it's down to concentration on the essentials -aviate, navigate, communicate..... plus ca change.