We are along way from opening up for those who have been vaccinated, for a few reasons.
First is obviously so many haven't had the chance to be vaccinated.
Second is that rates are so low that anyone assisting the spread of the disease is risking serious harm to the wider community, so while someone vaccinated mightn't have serious effects, they can still assist with the spread of the disease posing risks to others.
Thirdly, part of the success of lockdowns is that no-one can move around, meaning it is easier to police. If say 5% of the population had more freedom that is 150k people roaming Melbourne. How would anyone who shouldn't be be noticed?
Fourthly where would you go? Nowhere is open!
and Fifth, even once the population is well covered with vaccine, a decision needs to be made about how to protect those who cannot be vaccinated for health reasons, who would be at a higher risk of serious complications. As a society are we happy to just say bad luck, either stay locked away in a little bubble or risk death?