Since the 1.8.2 update, I've been noticing that I spawn along the edges of the map, rather than the middle. My thoery is that maybe a stronghold will be on the opposite side of the map from where you spawn so that 4j wouldn't have to tweak the stronghold spawning mechanisms as much. Again, this is just a theory since I haven't had enough time to test it.
Theory about Strongholds