The Governor-General is head of state and exercises powers that the Queen, who is the sovereign, cannot exercise. The head of state is a diplomatic term and not part of our constitution. The Governor-General is treated on foreign trips as the head of state. I'm not concerned with what other people think about our constitution. The British would be appalled if an Australian were crowned the King of England.
Republicanism is the purest form of democracy.
The people must fill every office of political importance. The head of state holds reserve powers of great importance. If we're going to change let's make sure we don't settle for an inferior arrangement. What's being proposed is a very shoddy model which will increase the power of politicians, and give enormous power to the prime minister to sack the president on a whim. I was effectively the head of state even when the Queen was in Australia.