The Australians were threatened by Indonesian naval and air power at various times. The RAN operated as task forces in areas China considered their backyard. Soviet support of Indonesia could have increased quickly in the 50's and 60's. The RAN has historically not operated alone, which is my point. If it is going alone, it has a limited range of operation it can afford.
If the F4 can do air defense from an Essex, it provides a chance of Australia using the design. However, that is one of the few good points on using an Essex. The problems are expense, even if at a reduced price, manning and operational costs, increased costs of acquiring Phantoms, costs of training pilots and ground crew, and lack of an ASW carrier, because these additional costs would deny the RAN the ability to afford a smaller air asset. If Australia had accepted an Essex when offered, sometime in the early '60's, how long could Australia operate the carrier. Even putting the crews of both the HMAS Melbourne and the HMAS Sydney into the Essex, becomes a strain, as their crews would equal the crew of the Essex class. I do not know which variant and upgrades were with the offered carrier. Would the RAN have the resources to escort the Essex? This is before the RAN had received the Perth class which were the only modern guided missile escorts available. There is no modern frigate until the 80's. If the RAN acquires an Essex, can it afford to order the Perth class? Would the RAAF be able to buy F 111's in this scenario? I think Hermes is the largest ship the RAN can effectively operate without extreme financial stress. Could it operate F8 Crusaders? Or is it limited to A4's? Could the RAN buy a Clemenceau? Again, with what moneys? What aircraft to use?
I would like to see the RAN acquire a larger, more capable