From an airline's perspective, letting them expire is one of the best ways, but classic awards are the worst way to reduce the liability. This is why since the first FF program was started in 1981 by AA, the points requirements for flights continue to be increased and other options such as ASA awards, points + pay, and redeeming for merchandise or hotels etc have been introduced. One of the ways to reduce the liability is to simply devalue the points by inflating the award charts.
If you redeem a classic award for say 100,000 points, they can only reduce the value of their liability by the value of those points. But if you redeem for an ASA award at say 500,000, they get to reduce the liability by 5 times as much.
Of course they still want you to continue earning them (particularly from partners, where it is cash in the door rather than an allocation of the price you paid for the ticket) but it is in their interest to have you redeem them as quickly and at as high a level as possible.
Yes. My bad. I always interpret JASAs as meaning the AFF version of JASAs - that being classic award level prices, but with any seat award conditions.
I think it's very bad for QF to offer status for such discounted fares.
I agree, the 600,000 points one way in J to London is great value for QFF - however I presume it's bad value for QFi?