I suppose the K/E/F/A-18F would be a Force Multiplier. You can read the headlines - "Australia to get new fighters, bombers & tankers - all in one Airframe!"
If I remember both the Typhoon and Rafale were regarded as too 'short on legs' for the RAAF requirement, and the F-18f is an in-service airframe. More importantly, youcan sell it to the polititians as 'not a new aircraft, but an improved version of what we have'