Bell Flyer, it might not be fashionable to admit it today, but the vast majority of those men who flocked to the colours in 1914 and in the years immediately afterwards considered themselves first and foremost British, and a threat to the Empire, to them, was a threat to everything they held sacred. (The exception were possibly those Australians of [Catholic] Irish descent, the Taliban of the day in the eyes of most Establishment Protestant Australians. However, this didn't stop them from joining up - and dying - in almost the same numbers as the 'British' Protestants.)
With 20/20 hindsight and today's attitudes, it's easy today to say it was all a waste and Australia was under no threat, but I think you'd be a brave man to say that if Imperial Germany had won WW1, it would not have had a hugely detrimental effect on Australia.
Perhaps a safer comment might be "it would have been a very different Australia (and world) in the 1920s and 30s." And today.
Some might argue that it would have been a far better Australia than the on we got. (Let's not forget that, along with New Zealand, Australia has the rather dubious distinction of suffering the highest per capita losses of any country - including France and Germany - in World War One. And they were all volunteers.) One historian argues that WW1 set Australia back 100 years, for we didn't just lose a very large proportion of one generation, we lost the cream of what some say was probably the best generation, the pioneers and the sons of the pioneers.
And let's not forget that quite a few of those pioneers were British born, and the type of Briton who had the get up and go to move halfway around the world to start a new life to what must have been very harsh conditions.
There was no way an Australian government of that day could have ignored the War in Europe. If Australia hadn't sent its own force to Britain's aid, the vast majority of the population - Arch Bishop Mannix aside - wanted to be involved in it and many would have gone under their own steam to England to join the British Army. Quite a few, fearing the untested colonial army would not ever get involved in the 'real' war, and wanting to fight with quality regiments, did just that anyway.
I won't argue that the political and military leaders of the day were careless of their men's lives.