What final good came from the deaths of Romeo and Juliet?

The final good that came from the deaths of Romeo and Juliet was the reconciliation of the two feuding families, the Montagues and Capulets. The deaths of their children brought them to recognize the futility of their conflict and to finally end their long-standing feud. This brought peace to Verona and allowed the city to finally move on from the violence and hatred that had plagued it for generations.