I agree with you about Darth Vader and the point you are making. I remember being offended at the end of the third movie when he is with Obi Wan and Yoda and they are best buds again. Really? Just because he finally decided to save his son and kill the emperor? That was just another selfish act.
I stopped being a Star Wars fan a long time ago. I think George Lucas had a few interesting ideas, but was a bad writer and a bad director. So I don’t expect anything seriously “deep” from his movies.
Having said that, I think the message was always that little Anakin was the Chosen One who could eliminate the Sith. The Jedi Council failed. Yoda failed. Obi-Wan failed. Luke failed. In the end, Dark Vader picked up the Emperor and tossed him to his apparent doom, thus fulfilling the prophecy and doing what only the Chosen One could do.
Lucas seems like something of a Buddhist and I see no hint of Christianity in the Star Wars universe. But one can find a hint of forgiveness and redemption in Dark Vader, I think.