People don't seem to realise that even though the door is unlocked and open a bit, they couldn't fall out. They are strapped in, and the airflow outside is enough to push the door back against them and it would take a big effort to get out the door and jump off the skids.
The lower static air pressure compared to cabin pressure makes the door open a bit, but the dynamic pressure against the partly-open door won't let it get much further.