what great ideas have been proposed that would improve or replace societal conventions, but haven’t been adopted because such a drastic change would be difficult this late in the game?

We have more than enough room and buildings to house everyone. We have more than enough food to feed everyone. We have the ability to have infinite free energy from nuclear, wind, and solar. We do not need to work anymore. We can effortlessly produce more than ever before with robots, computers, and efficient planning. Almost all modern scarcity is artificial, created on purpose by the wealthy so they can maintain their wealth.