I think DayZ would benefit massively from (optional) use of the Y coordinate in territories, it could be used to fine tune infected spawns and also add a large degree of customizability for community servers.

In the attached example, i've set up spawns for mutants in the Livonia bunker which adds a great horror element / some level of difficulty to acquiring the best loot in the map, but the spawns do not always work properly (The T3 warhead room spawns never function, they spawn above ground)

Adding support for Y coordinates to fix these issues (and others) would be a fantastic addition to the modding/community side of the game.