Or we take some small portion of that new surplus in productivity and share it among everyone by divorcing the need to work from the need to not starve.
No, it's much better for an elite class of superhumans to hoard all the wealth. After all they guided us to our current utopia, the least humanity can do is give them the vast majority of wealth.
who will redistribute stuff?
You are simply selecting new elites to be from the redistributor class (vanguard party, Nomenklatura, secret police etc), instead of the entrepreneural class.
Works well if you are the one redistributing stuff from "rich to poor", but it ends up as creating a new elite class, every single time