Regarding the OP's point of requesting to be advanced to an earlier flight on a 'cheap & inflexible' ticket, there are a few sides of this to consider.
Firstly, QF price tickets according to their inclusions (no surprise to most here) ie. seat, leg room, meal and *flexibility*, even the number of SCs and points earned. The theory is that if you want to be *guaranteed* these inclusions then fork out for the higher price ticket.
However, as the OP points out, QF could win loyalty by instructing staff to exercise discretion over these micro decisions - and for status flyers this more flexibility should be a factor. Sure, the discounted sale Red e-deal saver fare has TnC's up the kazoo disallowing this and that, but what is the harm letting our OP take the earlier flight?
Well, if he had been advanced to the earlier flight our AFF member would not be seething here on the forum nor plotting ways to make sure next time he flys his first destination will *not* be Qantas.com. But perhaps the QF logic (I think flawed) is that in theory our OP would instead blame his decision to book a cheap fare for his predicament and vow that 'in future' he will book the fully flexible fare bucket resulting in a bonanza of extra revenue on that and future tickets. But as we can see, this is not how things panned out.
Another factor is to consider is that the flight OP wanted to take will probably leave with the seat empty anyway, particularly if the flight is imminent. The seat that would now have been left empty on the later flight if OP was advanced comes into play. Our friend Johnny Come Lately business traveller with a company credit card who would dearly love to buy "any seat you have" on the aircraft, "I don't care how much it costs, I HAVE to be there for my very important meeting". But, what a shame, our OP - lubricated from his extra time in the QP - is now neatly ensconced in his uber cheap seat.... oh well, perhaps Johnny goes over to VA.
Sure, it won't happen every time, but to my reckoning, advancing the loyal frequent flyer is just common business sense.