There isn't a point in maintaining elements of another socioeconomic system in the chance we need to change in the future. As it is now things are scarce, but they may not always be scarce. However, we don't retain elements of utopia for that chance.

When you are taking about needs being met, as long as whatever energy breakthrough that gives us abundance functions and there is federalized planning, resources production can be shifted as needed to fill regular gaps in the system.

Each system has methods of patching itself (we have subsidization and state welfare systems etc). There is no reason to think a future system we adopt won't have any. If that's the case, why would it be opted?