Here's the thing - you simply don't always get a cheaper fare with a low cost carrier.
Try walking up to a jet star counter in the morning and asking how much it will cost for a ticket in the afternoon. Chances are it will be dearer than the Qantas ticket.
In most cases the so called LCC tickets are similar prices to QF unless you want to book in advance and haggle over a few bucks.
So when for example a PAX is forced to pay for a real air fare and are treated like crap, then they are right to complain.