What's the big deal about being one CC down? It is clear that other centres operate different crewing levels to LHR without compromising safety. I am sure that if you asked the pax if they wanted to delay the flight or do without (say) coffee, you would get a pretty definitive answer! Most people have places to be and a time to be there (even if it is just a holiday) and having paid their money, want the journey to happen. Or perhaps you have lost sight of the fact that you are employed to provide a service to the paying customer.
To BASSA, and many crew for that matter, it is a big deal to leave LHR with one crew down. BA actually needs dispension from the union to do so which is absolutely outrageous and I'm basing my opinion because I have been affected myself and stood on the ground with passengers on for hours whilst waiting for standby crew to arrive. In my opinion this is not to put the customers first.