I don’t think we’re capable of understanding “why” something is Hashem’s ratzon (which to me, is the only “morality” which counts), any more than we can understand “why” He exists. His ratzon is somehow a reflection of Him, and He is muchrach. He exists because He exists, His ratzon is His ratzon because it’s His ratzon, and morality is moral because it’s moral.
You keep on asking for another step of causation (“why”), but at some point it ends; it’s inherent – muchrach, and there’s no further step.