I bet if they had this tech during the development of TROS they would have used it. Ethically speaking, I’d say using this is justified if it helps a project achieve its artistic vision, particularly if it serves as a way to honor an actor that passed away.
I can’t remember: were you no longer interested in Leia saying “Come home!” to Ben when she reaches out? It would be a difficult line to sell but I still think it would be doable.