QANTAS doesn't owe me "xyz benefit", and I am not obliged to fly them (leaving aside corporate policy).
If one side wishes to change the bargain, then the other side (namely me) are free to go fly someone else.
I would state my PoV (once) and then move on.
F-lounge is "meh" anyway - there are far better places to spend your time than a lounge IMHO. Lounges are just there for when you have to be at the airport.
And there it is - in your opinion - you couldnt care one way or the other for the F lounge access - fair enough. For me - I value that benefit, others have their own perceived "value" attached to it and to other particular benefits.
As you have clearly indicated - company policy has you flying QF - so clearly your loyalty is caveat on that. It would seem to me that QFF has failed in your case as it hasn't done anything to obtain your loyalty to the product.
Obviously for you - you fly with whoever you fly with, and you'll take or leave whatever benefits are there or not. Fair enough - and I respect you for this.
For others like me who pay their own way - QFF has obtained my loyalty by providing me with published benefits and I repay those benefits by continuing to direct spend towards Qantas.
As you rightly say - if they change the bargain - then I am free to adjust my "loyalty" as a result.
Others here are simply saying that they have, in their particular individual circumstances, attached a perceived "value" to particular benefits and are unhappy with that being taken away.
Should they have the right to complain? Of course they should.
Beyond that - what should they do? Well, obviously they should make a decision if the change has materially affected their loyalty back to QF.
This particular thread is discussing peoples' views on the change so it is entirely relevant, and I don't consider it "whingeing" if people find this particular change to be dissatisfactory to them personally.