I think its a facet of diving history. BCs started at the front with horse-collar/fenzy type set ups and have been moving back ever since
The main difference is whether it keeps you head up in the water in all conditions especiall when unconcious. A Fenzy definitely will, a wing probably wont (esp when unconscious), where as a BC is a decent compromise.
I am all for the buoyancy being at the rear, but for a lot of novies the tradional jacket type can be comforting