Unfortunately, it was so expensive for the time that a lower cost solution was demanded by Congress... Hence the F-16 (One of the very few times a government listened to designers & the military about a less expensive/capable machine that made sense!)
So we have a similar situation now... The F-22 for Air superiority and a less capable, but quite a bit less expensive multi-roll aircraft for everything else...
Still, the idea of an F-35 replacing an A-10 is just about the most ridiculous thing I’ve ever heard.... No way will it be able to take the pounding, provide the loiter time, be able to gun anything that moves on the ground, and still carry 16,000 lbs. of other ordinance and bring its pilot back alive even if the aircraft isn't recoverable!
That kinda complete air superiority is difficult to establish unless you have overwhelming superiority over your enemy in terms of numbers and technology. Thats not something Australia has. It would make more sense to buy multi-role aircraft that can do a combination of ground strikes and air defense.
The Mig 23 is useless but the Flankers are formidable. The F-15s are fast becoming outdated and would at best just hold ground against the Sukhois. Australia doesnt have much options.
We have to lobby to them to keep the A-10 for as long as its shelf life says.