Even with one ear, you can tell whether a sound is coming from behind you, or whether it is to your right or left.
The shape of your ear directs sound into the ear cavity differently depending on its relative location.
One-ear musicians can't perceive a stereo (def: from the greek for solid - no mention of "two") image the way most of us can, so we can't blame Brian for not thinking in terms of creating a stereo image with his productions. Multiple ears and transducers are definately better at experiencing acoustic spaces, and unless you regularly work in an anechoic chamber, we rarely hear anything that is not influenced by the room around it.