Cockpit visits had their place in aviation in their time. But that time passed when a bunch of terrorists decided to take over planes all too easily and cut the pilots throats, and then commit mass suicide, and an African nutter (who was free in no time) decided that it was time for a 747 load of people to die. So the locked door policy is here for good! Whatever effect it has on the pilots or the passengers is irrelevant- the job must be done and peoples' safety assured as far as is possible. Period.