Someone with ATC background could confirm this but I believe the reason the Rwy34 VOR @ ML is offset and why ATC prefer its use is that it follows the course of the Maribynong River and so passes between built up areas and not over them which makes for a kind of pseudo noise abatement approach. The good residents of Keilor and others near the approach to Rwy34 have made a lot of noise about noise in the past apparently !