You stated an opinion, and then object to those who disagree with you?

Well, here are a few more reasons:

-- you can't just unload an airplane anywhere on the paved surfaces of an airport, since people can't walk around near active jet engines. most airports are not exactly overflowing with space for this sort of activity.

-- once you open up the pax doors & baggage, it takes a while to finish what you started. if a gate opens up in the interim, you're in trouble...

-- you need baggage facilities to unload the luggage, and staff, and stairs, and busses/drivers, and people to escort the pax to the busses/to the terminal. Where are those extra people coming from, and why do you think they won't be otherwise occupied?

-- sometimes, the world doesn't revolve around YOUR flight. Just maybe, the airline may need to offer up 1 flight as a sacrifice to keep most of the rest of the ops on schedule.

Flame away!