Why did we buy

[darthpanda]

Who said that RAAF only keep those Rhino's for 5 years? You must understand in military term:
Temporary solution = THE solution

The reason the for F-111 to retire is: MONEY

1. High maintenance cost
like you said F-111 is from the 70's and with variable-sweep wings, that will make her very very maintenance intensive. Most of the parts are out of production years ago, that meant a lots of $$$$$$ to find and get parts.

2. High Operation cost
Then because she has a lots of moving parts for her variable-sweep wings, That meant she needs a lots of ground crew operate her, more ground crew = more cost.

On the other hand F-111 has reached the limitation for upgrade, there are limited space on board for new modern avionic and the limited computer capacity which needed for modern air combat.

Especially after most potential enemy in the area are equipped with Flankers now, you will need something better the old F-111.

[navybrat85]

I don't know a whole lot about the F-111, but eventually the time comes when the old war horses must concede their stables to the new generation. I didn't want to see the Tomcat retired, and I was sad when they retired it, but if it wasn't already so, the Tomcat, like the Aardvark, would have become more a burden than it's worth to keep around. The sentimental feelings towards these work horse aircraft are understandable, but sentiment alone does not provide for good national defense. If it did, then the USAF would still be flying Mustangs and Flying Forts.

[Colosseum]

Nothing wrong with retiring them... they gave good honorable service while they were part of the RAAF, hopefully the Australians get to keep a few around for museum aircraft and for private owners to fly around.

[blackbuck]

There's an F-111 in a museum at RAF Cosford not too far from where I live and I must admit they are fantastic planes aesthetically and from a technical point of view. As Colo says hope some of them are kept back for preservation.