Sorry, Leady, but it has everything to do with zealotry.
Zealotry pushed half-truths during 11/11, the G-Airspace Trial, Airspace 2000, Son of Airspace 2000, and that basket-case NAS. In my opinion, the protagonists were less than truthful; however influence and profile reigned and politicians and bureaucrats alike were sucked in to the tune of untold millions.
There are only two legitimate avenues to address airspace change, and they go hand-in-hand. A proper risk-management analysis and, most importantly, a robust cost/benefit analysis. Neither was done in the aforementioned disasters. Influence and half-truths ruled the roost to the cost of the taxpayer. They were all pet projects pushed with flawed underlying assumptions that were ignored in the interests of ramming home change while influence was there with the ignorant.
And this goes to the nub of zealotry, Leady. The dumb in government were unduly influenced by half-truths that were shamelessly sold as fact.
The 'Australia is unique' line was constantly peddled by zealots to back change. No risk management and no cost/benefit. Just an airy-fairy argument that we are 'unique.'
But, as I have related, we are not. I'll reiterate - Canadian offshore Class F is also designated as D; and you need a clearance. NZ offshore MOAs now require a clearance and have for the last eight years.
Your argument that it's 'illegal' is peripheral to the fact that other sovereign nations pursue similar procedures. Which is way, way counter to the accusations of 'uniqueness' in Australia. This was the fundamental, fundamental justification for airspace change in Australia and it was just so much tripe!
Arguments based on fact I have no issue with. Arguments based on BS, with a concomitant loss off taxpayer dollars, have seen an ongoing, divisive series of exercises that we don't need to revisit.
You want change Leady? Risk management and cost/benefit and I'll back you to the hilt if the numbers come out on the positive side of the ledger! 'We are unique' just doesn't wash.