> Could we not keep the optimizing aspects of market economies even in a world where people are safe enough to say no?

That requires the provision of safety and security outside of market mechanisms. This is where "basic income" (security against destitution, but still using the market) and "universal healthcare" (variety of not-quite-market options) are coming from.

It also requires some kind of firewalling of political and psychological security against market mechanisms, otherwise the invisible hand will reach back in to exploit people's unsafety.