C100driver, the A330 was flown under the same 180 mins ETOPS as Air NZ's B777's and I don't know what the difference is between the two types Engine Out Cruise speeds but as the B777 cruises at 0.84 whereas the A330 cruises about 0.80-0.81, I suspect that there is a difference. As you are aware, long haul flight planning tries to fly the most efficient route wrt winds but when you have to stay within the ETOPS range of Christmas Island, it frequently means a less than optimum route. The QF A330 was averaging approximately 90 minutes more than what the QF B744 would take on the LAX-AKL sector.
Computer Reservation Systems prioritise flights according to shortest elapsed time so the fact that the Air NZ B777's cruised faster gave them a significant commercial advantage wrt bookings over the QF A330 operation. The whole reason QF put the A330 on the route was to position it to LAX so it could operate the route to JFK - the B744 had suddenly become "inefficient" due to all the underfloor freight being shifted to Atlas freighter aircraft.
TCOB, the route was closed due to shrinking load factors- not due to the aircraft being required for domestic factors. The 2 class 412 seat B744's that were used previously had extremely high load factors and, as Air NZ showed when they put on their additional service, the demand was still there - just not on the A330 product that QF was offering.