1. Time is money to people who work. Time spent in seat at gate is wasted.
2. Few people check luggage anymore so the sooner they are off the aircraft, the sooner they are at their destination.
3. Lines at customs/immigration
4. Tight connections
5. Scheduled calls
6. Bodily functions
7. Taxi lines (at smaller stations)
8. Getting off aircraft before the people who wedged their steamer trunk into the OH and now need 5 mins to unwedge it.