Perhaps you misunderstand Any Seat Award. As the name suggests Any Seat Awards could/can take ANY SEAT on the flight. The inherent part of that is that they take existing fares that are available for sale on the flight, from the cheapest available fare class. What is called a Marginal Any Seat Award is what happened when a classic award was available on the same flight - this is fare class U in business. If a classic award was available then a U fare was available. Buying an Any Seat Award would take one of the U fares. The same would happen in economy where a Marginal Any Seat Award would take an X class fare if available. It is the marginal ASA, only, that have been stopped. Those Any Seat Awards that are taking U, P and X fares. Qantas only have a problem with the Marginal ASA. Those fares DO actually depend on taking a classic award seat. If it does not take a classic award seat it is not a Marginal Any Seat Award. The Marginal ASA MUST be the same as a classic award otherwise it isn't an Marginal ASA.
Any Seat Awards* do still exist, just only the ASA that will take paid fare classes, J, I, C in business. This also means the only problem Qantas had was the return, and hence pricing, of the ASA that used classic award fare classes.
Sorry to sound lecture-ry, just your comment suggested a mis-understanding about Marginal ASA.
* Even if I have terminological problems with writing this.
The way it was set up is exactly KISS. It used the existing fare structure.