Perhaps I can help here.
The discussions here seem to be tending towards the lines expressed in the recent ASPI paper, which I'd summarise as:
LHD/F-35B can't be a 'true carrier'
Time spent on F-35B off LHD would detract from the LHD's main role
It won't be effective anyway
If you want fixed wing aircraft at sea the only answer is a USN sized carrier
The ADF can do without it
I'll try to address those. First point is true, if you think the only effective carrier is a great big one. But it's not true. The RN and the USMC have shown time and again the difference a small ship delivering STOVL air direct to the fight. The future for sea based fixed wing, unless you are USN or China (and possibly India) is going to be F-35B on ships of various sizes, all smaller than CVNs. In my view (and I know others will disagree) the ADF has a chance to gain this capability.
Yes, time spent on F-35B ops would 'detract' from the 'main role'. But things change. Roles change. STOVL is not anywhere near as hard to set up at sea as cat and trap. But it's a balance, and I agree that the sums and the assessments have to be done on how the LHD time would be sliced up. But saying 'we can't do it because we musn't change our plans' is about the weakest argument against the idea.
Effectiveness - I honestly don't think some here on this thread understand just how effective a smallish force of F-35Bs, in there right place, could be. Or how limited land based air at long ranges actually is. Let's put it like this - if the LHD force is, say, 300 miles from land based air, just how many aircraft do you think a land based F-35A force could put over the fleet on a 24 hour basis? Possibly 2, even if they had the tanker capacity, which they don't. Combat duration over the fleet measured in tens of minutes. Time to react to a threat? Those 48 hour ATO planning cycles mean the fleet will have to make do with what's been planned, not what they might need. (And I speak as a survivor of the cold war when the RN was promised that a whole (large) squadron of RAF Phantoms would provide fleet air defence. It ran out around 90 miles off the UK coast). Now think of 6 F-35Bs on the LHD deck, at an 'alert 3' posture for air defence or strike missions. Oh, and look up some of the sums for just how huge the costs are for maintaining constant combat air presence at these sort of ranges.
Again, for clarity - the answer is no longer the huge ship, unless you are a superpower. STOVL and ships like the LHD offer a smaller player the chance to put real combat power (not to mention a fairly awesome ISTAR asset) where it's needed, not where it has to be based.
Does the ADF need it? Don't know, has to be their call. But they need to reflect on the vital roles sea based fixed wing air has played in campaign after campaign over the past 35 years. They need to look at just how frequently Host Nation Support (HNS) has been withdrawn for land based aircraft (the answer, by the way, is very). They need to have a realistic threat scenario which includes a proper assessment of air threats to a surface task force.
And finally, if the argument against F-35B on board is 'we would never plan to put an ADF task force where it can't have 24 hour cover from land based air', then get ready for some short and limited duration deployments.
The one line I very much agree with is that the ADF has time to look at this properly. The Australian buy of 70 odd F-35As is large and should meet RAAF requirements for some time. Let's make sure that a properly constituted panel of experts takes an objective look at this. The UK has (sadly) shown what happens when Defence Reviews are rushed and then hijacked by singe service politics. And sea based fixed wing is, make no mistake, always a hugely (inter service) political issue.
Best Regards
Engines101