I agree with a lot you say there, a mature nation would elect its head of state.
Until the noisy conservative monarchists move on to a better place, I dont see any point in focusing on details yet.
Until this happens and politicians stop putting up referendums giving unpalatable choices i see the cause as futile.
The only question I would like to see in a referendum is "Should Australia become a republic"
If the people answer yes to this, then we can focus on the structure and mechanisms.