A certain seniority system should be in place while within a company to be able to sort out such things as a bid lines, requests, leave and staff travel for example, however I do believe the current system of say being a Captain or F/O at one airline and not being able to move to a company that is more suitable (money, lifestyle/roster, location, quick command, family matters or whatever) and not be able to retain your current rank is outdated and being used against us, face it, as others have said airlines would have to improve money, lifestyle/roster, location, quick commands, family matters or whatever to keep employees, so not to waste money on training/endorsments and the like. Also not all pilots are after the same thing, as you get older your priorities change so why shouldn't we be able to change companies as our lifestyle changes! Some may stay, some may go but staying because I have to take a demotion or a pay cut to join another company just isn't right.