The selection procedure for most western majors is such (talking from a west European perspective, at least) that it is rare to see people coming up whom are not capable of doing the job from the left seat. The training dept. and/or chief pilots should deal with the few who are not up to snuff. Safety would be adversely affected if the guy in the right seat gains by putting down the guy in the left seat. You are both there to make the flight as safe as possible. Changing the seniority system will decreases safety across the board, drive up wages, and is not good for the airline business. It might not be ideal, but it is the best of all scenarios I can think of. I ride the right seat on a 747, am 37 years old and have thirteen years seniority with a major European airline.