Prior to launch there was an official survey done by Ausgamers on behalf of Blizzard and the consensus was to have US servers for various reasons which i forget. Having played EQ for 3 years under the same circumstances at the time i thought most people would vote for Australian based servers but that wasn't the case.
EDIT
I remember now. Blizzard asked if we were prepared to wait 6 months after launch for Australian servers and the result was a resounding no and thus they scrapped that idea.
Link -
AusGamers.com - Australia's Games Community