I remember reading an answer to this question in an Airlners World (or similar) magazine about 5 or 6 years ago. The exact details have got lost in the mists of time but the main points were something along the lines of...
"... The bogies hang forward do that the wheels are parallel to the main spine (fore/aft beams of the aircraft structure) beams when the gear retracts. The main reason for this was during the design of the 767, there was a large increase in the price of oil (Middle East oil crisis, I believe). Therefore, the wing design was changed (sweep increased and moved slightly further back on the fuselage to improve fuel efficiency) As a result, the bogies then needed to tilt forward so that the wheels were parallel with above mentioned spine beam. (Something to do with reducing redesign....?)
Hope this helps. As I put in above, I am dragging this out from the "totally useless things to remember" bit of my brain, so apologies in advance for any errors.
Regards,
Shuttlebus