How many times do we have to go through this? CX, JL, and SQ all have something QF doesn't have - that is connections from Australia to long haul flights via their hubs in Asia. It's the long haul flights that support the big dollar premiums for PE.
Geographically, Qantas does have PE to Asia, as in far western Asia, ie. DXB. But for its destinations in what we consider Asia (ie eastern part of Asia) it has no connections to long haul flights, and people (as in enough people, some do, but it seems not enough) don't seem to be willing to pay 2x-2.5x the price of an economy fare for a 7-8 hour flight. Maybe NRT will work as it is further, but I know between SIN & MEL I would not pay $2k to sit in premium economy for a 7 hour flight, if economy is $800. Now if PE was only $1k, I would, but is that profitable for an airline?
Maybe in 12 months time, when QF is back making lots of money (haha - although the capacity war does seem over), and sees a good return from the capital investment in upgrading the 330's to include PE , I will be happy to eat my words. But in the meantime, it seems the carriers most successfully deploying PE do so on the long 12hr+ journeys, with the ability to fill unfilled seats at the last minute by discounting shorter sectors (like BA do between SYD & SIN).