According to the captains testimony, he had had prior experiences with it nearly injuring a ground crew, and also witnessed a door slamming to the ground and bouncing back up several feet. I don't see how that couldn't cause any damage to the hinges or frame. Maybe it wouldn't be obvious but still could be internal. Also, a mechanic had come out to that captain and said this is very dangerous, to just let the door fall open...regardless of what the MEL said.

So we need to realize what the captain was thinking. He had seen this situation before and based on his experience, he made decision. Many of us have probably not seen this situation, so we would probably take the airplane. Point is, we've all had different experiences in one way or another, and base our decision making upon that.