One issue is that it can be really difficult to organise and be certain it will work. Our recent cruise ended in Dubai and BA moved our flight to be really early in the morning, which meant leaving the ship before the formal disembarkation time. We emailed beforehand and we’re told it should be OK, but to let customer relations know once we were onboard. We did so and were told it might or might not be possible - they would let us know a couple of days before the end of the cruise. In the end it was OK. We had to take our luggage off ourselves. What was really strange - we didn’t see any port officials - no immigration, no customs etc. Ship’s porters took our luggage from us at the top of the gangway & wheeled it straight through the terminal to the taxi rank with us following.