Its all about TURNAROUND !!!
It takes on average 75 minutes to turn an 332 around, and as you all know MEL SYD BNE turnarounds are sceduled at 40 minutes.
Put it on a SYD/MEL/SYD/ rotation with 80 minute block times each way - factor in 75 minute turnarounds - no way thats economical.
A 767 can be back in SYD and operating its next sector in 4 hours, the 332 would take over 5 hours !!!
Perth is an ideal route, and yes J Class seats on the 332 suck big time !!!