Speaking from many years of domestic flying experience, including a lot of Red-Eyes: the problem is I don't believe the demand is there to have a 350+ seat plane with 65 Skybeds doing the PER-SYD Red-Eye. Sounds lovely for a pax but I reckon that would be a loss-maker overall. AT MOST what is needed is an A330 doing the Red-Eye but we seem to be short of those, for some reason.....
And yes, I still question the whole cost/value/benefit thing of a Skybed on a "relatively" short sector such as PER-SYD. Granted, it's a miserable night-time leg but you would only be tucked up in the Skybed proper for about 2.5 hours, 3 hours max. But I'm sorry, but these are expensive things and are not in unlimited supply. They are used on genuine long haul routes where people will get/want to get 6,8+ hours of sleep. The airline could not justify the return on the investment putting them on PER-SYD at the expense of foregoing them elsewhere on longer sectors.
So why do SYD-PER-SYD during the DAYTIME with the 744/Skybed? Exactly as they say: using the aircraft when they would otherwise be sitting on the ground, prior to heading to Europe overnight. This is all about increasing total capacity and you'd do it with A330's if they were available (again, where are they...?). The Skybed is just a bonus and the marketers are playing it up - maybe they shouldn't.
Domestically, on SYD-PER-SYD you provide a J class product that is roomy enough, seat reclines a good distance and is private (ie, no 7th seat -something QF has stuffed around with for years, going back and forth on that 4 times so far, by my count).
There will always be people who want more and more but at the end of the day are not prepared to pay for it. In the case of a Skybed on the PER-SYD Red-Eye: it would cost QF a LOT in foregone revenue if it sacrificed European/USA Skybed services in order to put it on Red-Eye. Would pax pay an increased J-class fare to offset that? Not a chance.