While I do agree that the FO didn't handle things very well, I will say this. It is very annoying to get to a gate on time, wait around till 15-20 mins till departure, then have the pax follow you down the jetbirdge onto the plane. If the gate agent screwed up and forgot about us, thats fine, I understand. But why dump all the pressure to get out on-time on the crew when they haven't even had a chance to power up the plane and do any preflight work? If its your screw up than man up and take some responsibility, chances are the crew will do more to help things out this way. If you take enough (legitimate) late-outs maybe someone higher on the food chain will consider hiring back some of your lost compadres.