I used to share your view. But then read that EU authorities have decided this is an extraordinary event (although they are still saying full refunds are required).
The decision to stop flying may be a commercial one, but that has been forced upon them by governments closing borders, restricting anything but non-essential travel, and also companies being required to still follow OH&S laws - they need to make sure their staff are safe.
All those restrictions mean that they can't fill their planes due to government action.
I agree that the pendulum is swinging from "no way" to "perhaps" when it comes to "will airlines get away with this excuse?" Each of the issues you've raised is relevant, but until the ACCC and / or courts are willing to fundamentally redefine what has up to now been allowed to qualify as "government restrictions", I don't think we've swung the pendulum all the way to "yes" in Australia just yet.
Generally speaking, EU law is more protective of consumers than ours, so if they're ruling in favour of businesses in this case, it may be a sign of things to come here. However, several countries in the EU have outright banned airlines from flying, and because the entire EU has to work as one body, effectively the rules of the strictest member state have to be treated as applicable to all to be aligned and equitable. That's not the case in Australia. Even with hard border closures, no one is "stopping" airlines from flying when / if they want to. They just don't want to because their commercial environment has changed.
Granted it's changed in part due to government restrictions, but the government imposes all kinds of conditions / restrictions on businesses that impact their ability to operate and maximise commercial profitability, often even after industries are well-established. Think financial regulations, privacy and data protection, licensing, labour laws, etc. Those restrictions may fundamentally impact business. Certainly, the current developments in this industry are unprecedented in terms of sudden scope and timeline of implementation.
But in any case, if a consumer has paid for a service and the business can no longer deliver (or, as I would suggest in this case, chooses not to based on restrictions that make doing so unprofitable -- which is understandable), it still comes down to who can best absorb that loss, and I don't think there's a compelling enough argument yet in this case to say it ought to be VA pax. After all, it's not just businesses suffering at whiplash speed, and I don't see why some bloke who two months ago planned a trip to Disneyland and bought tickets on VA but now finds himself standing in line at Centre Link this week should be carrying the loss for VA.
Understandable to stop flying; not understandable to say the passenger has to eat the loss.