Can I ask why you say it is fair enough? Why should a WP be able to get a business seat released, subject to Qantas' decison, but never an economy seat?
My suspicion is that load factors etc. are high enough that they can derive more revenue by not having to release more seats than needed for domestic Economy. Don't forget there's often many last minute bookings on some flights (especially in crazy times) that easily fills up seats (even the odd 1 or 2 hole seats kept for the odd rare WP priority Y purchase). On international, that's a much less common occurrence.
I'm surprised and not surprised that you can put in a request for Classic domestic Business, as there are usually so few physical seats that often either an award seat is there or there really is not one - there's almost no in-between.
FWIW except for the crazy times finding Classic Y and J seats is often not a problem for me online.
For international operations with larger aircraft (equals more seats) and especially more physical seats to fill in premium classes it's a different ball game. I'm assuming that requesting for Classic international Economy is allowed, especially if you are requesting more than 1 or 2 seats.
In a sense, you could argue why don't they just allow it (requesting Classic domestic Economy). The reality may be, however, that you'll often be greeted with a response of
no, unless the flight is pretty dead (in which case why aren't there Classic Economy seats available on it anyway?)
I'd assume that in pinches, P1s can bend the system easily to get what they want.
