A good story has a single theme centered around it; it has one central concept that is said repeatedly and consistently.
A good story is like a good song; it has a beginning, a middle, and an end. The parts have an internal logic that works throughout it and binds the entire thing together.
A good story is like ceramics, where you take a lump of clay and gradually reduce and shape the excess to get to the core.
A good story is a process of deconstructing why something matters and what the one point truly is. Asking constantly why is a good way to deconstruct.
A good story stands on its own in that it is complete with the one point it tries to make. It doesn't require any other points.
A good story teaches something new or introduces a new concept to the world. It opens the mind to a new possibility or teaching that was previously unconsidered before.