The longevity based payscale is a large part of the problem, not seniority.

Since there is absolutely no fair, objective means of gauging individual pilot performance, seniority is the the only equitable way to award schedules, domiciles, and upgrades. Otherwise, everything goes to the @ss-lickers...how would you like having to spend your days off hanging around the CP's office to curry favor in order to get that upgrade?