I think I could answer that. You see, false hopes and disappointment. In Badlands, when attackers are thinking about their possible routes and paths, they completely ignore that hatch, knowing they cannot access it. With one way doors players psychology is somewhat different.
Upon seeing the doors, new players will immediately think that they can go through there, but will meet disappointment, while older players will face two choices - either wait there, ambush whoever comes through the door and run in while it's still open (perhaps not meeting anyone, dieing or not being fast enough with the doors, thus being disappointed), or abandon this path to their destination and feel somewhat disappointed (remember, universally in any players mind any openable door is a pathway to their destination, and not entering one when you want to disappoints the player (it's again somewhat different with enemies spawn doors, as they don't exactly lead the player to their destination, thus players have less interest in entering them)).
I'm not saying that they don't work from gameplay perspective, I'm saying that players minds are not too keen on these things. From this point of view a ledge would probably work better. But from gameplay? Who knows, man.
Who knows.