An interesting discussion which suggests that the thread title should be changed to "Should CASA change the alternate requirements", because that's what it really boils down to. The CASA policy is that, if a destination is forecast to be below alternate criteria 30 minutes either side of your ETA you need to carry an alternate; but if it's not, then you don't have to. It's really just as simple as that, and the QF fuel policy abides by these regulations.
If nothing else, it will sting the beancounters into action to make BOM do a better job.
I can see two possible outcomes if more pressure were to be put on the BOM:
1. Under the present regs, they could become arch-conservative and if there is the SLIGHTEST possibility of requiring an alternate, then they will forecast accordingly; or
2. If the regs changed and every aircraft carried an alternate, their forecasting could become even worse with diversions becoming more common.
Neither outcome is desirable. As Mark Twain said, "Everybody complains about the weather, but nobody does anything about it".
On a different, but relevant note. A recent AIPA newsletter said that Sydney hopes to have Cat II capability on both 16R and 34L by the end of this year. Apparently the sticking point has been the construction of suitable lengths of HIALS for each runway.