Any coherent ethical theory must aim to attain a world-state with less suffering.
I think that’s a misunderstanding of the word “coherent”. A coherent ethical theory is one that aims to attain a world state that is logically consistent with itself. Maybe that means less suffering. Maybe that means more suffering. Maybe that means extreme suffering for some and very little suffering for others. All of these world-states are logically consistent, and, thus it’s possible to create coherent ethical theories that justify any of them.
I think that’s a misunderstanding of the word “coherent”. A coherent ethical theory is one that aims to attain a world state that is logically consistent with itself. Maybe that means less suffering. Maybe that means more suffering. Maybe that means extreme suffering for some and very little suffering for others. All of these world-states are logically consistent, and, thus it’s possible to create coherent ethical theories that justify any of them.