Unfortunately, BoM aviation forecasts have never been particularly accurate, but there has never been any studies or stats kept to see exactly how accurate/inaccurate they are. At the end of the day it is just educated guessing. Because the regs dictate that only BoM weather can be used operationally, airlines are hamstrung even if they want to use in-house forecasting. There is no competition, and no accountability. The regulator won't change anything, as they don't want different carriers using different interpretations to work out individual fuel requirements, and likely feel that airline's Met. Depts would always forecast a little more sympathetically, shall we say.
Part of the procedural problem also is that the system has not really adapted from the long ago abolition of Ops Control and Flight Service, in so far as their flight following duties went. Airlines have not had to develop their own dispatch/flight following (call it what you will), as they have always had the Service Provider do it for them. And frankly, there's not enough of them, and they are too busy doing what they are actually paid for - separating aircraft. That's probably why you only get weather updates an hour out. Either it's a tacit admission that the forecasts aren't much good outside that period, or they don't have the wherewithall to manage it more than that. Worrying about what the weather at your alternate is doing is probably not that high on the controllers priority list as he deals with the deteriorating traffic situation at your destination.
I guess the generally good weather in Australia has allowed this situation to develop, and the very rare "near miss " like this will probably not change it.