This is true, but neither of these things are what Luke is after. Luke's motivations in RoTJ are a) becoming a full Jedi Knight; and b) his father's redemption

This is true, but neither of these things are what Luke is after. Luke's motivations in RoTJ are a) becoming a full Jedi Knight; and b) his father's redemption - not his death. He achieves both of these, and Vader would not have turned from the dark side without him there.