I stopped considering Anakin fully redeemed by the end of ROTJ a long time ago. I don't care how much the movie wants me to swallow it's happy ending, and it is a happy ending, but Anakin doesn't get off that easy. Not by a long shot. That man has a LOT to answer for.
In ROTJ he comes back to the Light Side, he kills the emperor, he helps the Rebels in a massive way, he helps destroy the Death Star, and he gives his life doing it...But Not even everything he did that day could ever make up for the countless billions that he helped kill while he was a Sith. You don't just wipe that slate clean. Something like that takes work, and death isn't a get out of jail free card. That's one reason I want to see Anakin as a force ghost. He should have to help Luke and others that are fighting the darkness. That should be his penance. He shouldn't get off scott free just because he kicked the bucket.
The Art Book for TFA shows concept art for an Anakin force ghost because when they were hammering out the story in the early Arndt days it was thought that Anakin might appear in Episode 7. The note with the concept art says that they conceived his force ghost as one that shifts between Anakin and Vader, because the dark and the light is a part of who Anakin is. So he carries that with him even in the afterlife. And I like that, because it makes him not only imperfect in death but also goes back to the fact that he is a creation of the Force and the Force is both Light and Dark.
Of course, Rian could throw all that out and do something entirely different with Anakin, or nothing at all.
