RVSM
Yes indeed the lack of RVSM was one of many holes that lined up that night. This has been overshadowed by other issues, but the lack of RVSM played a critical role. The need to be able to climb above RVSM airspace was presumably the reason full fuel was not uplifted at Apia. Full fuel would at least have allowed a few more approaches at Norfolk, and maybe they would have got a break. More importantly, full fuel may have made diversion to Noumea an easy decision when DJ first became aware of deteriorating weather at Norfolk (by the time he became aware, it was not clear he could reach Noumea).
With no RVSM, the only way they could have flown Apia - Melbourne and carried an alternate would have been to go via Noumea, or Nadi & Norfolk (shorter than Noumea, but two stops).
Its difficult to escape the conclusion there were a lot of corners cut, and they were very exposed to any bad luck (unexpected headwinds, deteriorating conditions). The CASA special audit reviewed PelAir's records, and determined there were three instances over the previous couple of years when PelAir landed at Norfolk without alternate fuel (well, two landings and one ditching). Sooner or later the holes were going to line up.
That statistic itself is striking. Three flights to Norfolk without alternate fuel, and only 2 successful landings.
The real question is on whose watch were all these corners allowed to be cut. Most people here feel DJ should carry some responsibility, but only some.