Before going off half-cocked, consider for a start, that you are wrong. RAAF Amberley is now Defence's biggest airbase. Secondly, why don't you pause for a bit, take a deep breath and then actually have a look at where RAAF has it's bases?
Here is a nice pretty map, showing all of RAAF's active bases.
To which you can add 3x "bare bases" capable of being activated in a time of war. These include RAAF Scherger, located at Weipa in far Northern Queensland, RAAF Learmonth at Exmouth in North Western Australia and RAAF Base Curtin at Derby North Western Australia. All of which are positioned and designed, to accomodate DEPLOYED RAAF and ADF elements, exactly where you think they should be... In this case, ADF and Government happen to as well.
Here is the full list of operational and bare RAAF bases within AustrRalia, plus RAAF Butterworth, which is still maintained with a RAAF detachment.
RAAF can operate tactical fighter elements from the overwhelming majority of these bases and does so on a regular basis. RAAF regularly deploys forces and tests it's capability to do so, constantly.
The REASON that RAAF Williamtown is the primary home of RAAF's fighter force is it is the traditional home of RAAF fighter force. It was once considered important to maintain some strategic depth in defence, it might just be the case that, that is STILL important today... Wouldn't it be a great idea to base our entire Air Force in the north of the Country, if such a surprise attack occurred?
Don't you think therefore, that perhaps it is not an entirely unreasonable proposition to situate the bulk of our air combat capability in an area that actually makes use of our geographic reality and denies same to a potential enemy? It is a lot easier to fly fighter elements to a deployment base than it is to reconstitute a destroyed air force...
On top of this, defence industry capability to support our fighters is based there. RAAF's Operational Conversion Unit is based there and the base is big enough and modern enough to accomodate the fighter squadrons, OCU, maintenance and training facilities, plus it has good access to on-shore and off-shore training areas.
The "bombed out base" will be repaired I imagine, with aircraft dispersed before it is struck. Force protection measures are considered before operations are conducted and implemented whilst operations are being conducted. There are no guarantees in war. What if the enemy sinks our pseudo-carrier one might ask? What fire support will the digs have then? Investing in F-35B would most likely soak up all the funding for a cruise missile capability and probably all the other fire support projects ADF wants as well. The list of potential "whatifs" is endless.
Exactly what "fixed wing carrier ops" have we replaced, btw? Australia hasn't run a fixed wing carrier capability since 1982... Funnily enough, we've survived nearly 30 years now without a carrier. The world hasn't ended in that time and we've run plenty of amphibious operations in Asia and the South Pacific...
As already outlined above, you've forgotten entirely that RAAF has a well practiced and sound deployment capability with it's fighter force. Defence of Australia operations would NOT be run from fighters based at Williamtown, so some of the more ridiculous arguments in that little rant do not even apply.
I think you are a little bit too concerned about "CAS" too. The ADF is becoming increasingly joint. The digs on the ground couldn't care less where a bomb comes from, so long as it suppresses or destroys the enemy when they need it. JTAC's control all in-direct fires in CAS situations nowadays and don't overly care either what delivers the effect, so long as it IS delivered and achieves the mission.
Under current plans, Navy is going to have 127mm guns with long ranged land attack capabilities. It is also going to have a long ranged cruise missile capability. Whether this is Tomahawk or some other missile system remains to be seen.
RAN and Army are also likely to have an attack helicopter capability present in theatre in any amphibious operations (Navy has a requirement for a short ranged air to surface missile capability from it's new maritime warfare helos) and the digs obviously will have the full range of direct and in-direct fires that Army will be able to deploy on any of these operations.
That is a far better fire support capability than ADF can generate now and it is a far better fire support capability than ADF had when we DID run a carrier. Hoping for more is unrealistic, especially when the boats we are buying aren't suited to it.
The problem with your argument is that you do not consider reality. Heard about the problems with manning the submarine squadron, have you? Well they are based in Perth. Imagine if it were based on the North West Coast of Australia. Who exactly would want to join then? The majority of our major capabilities are based near our population and industrial bases, for what should be obvious reasons. If you can't grasp that, then perhaps doing a little critical thinking, couldn't hurt.