Whoever said that 'Let It Be' was meant to be stripped down originally was correct, but they gave it to Phil Spector because they thought it sounded like shit, to be frank. So for Paul McCartney to come back and say "this is the way it was originally intended" (while correct) and release it, is kind of misleading given that George and John are dead. This circumstance is slightly different, though, because we do know that it was meant to be stripped down to begin with.
Back to the point - I wouldn't say "power to Lucas" now that he's changed the OT on the basis that he owns the films, because he didn't single-handedly make the films. Perhaps if Kurtz, Kasdan, Kershner (or the relevant director for each film), AND Lucas all agreed to go back and change the films, it would have my blessing. It isn't all Lucas' art - he collaborated. He directed ANH, sure, but aside from that, he wrote the STORY. And that is a very loose thing. I could write ten pages full of ideas and that could be the story for a movie (in fact, I'm doing it right now!). Aside from that, it's safe to assume that George sat down with other people like Kasdan, and worked through ideas, some of which would have been rejected because they were probably crap (which, as you can see, probably isn't what happened with the prequels) and Kasdan (among other, like Leigh Brackett) wrote the SCREENPLAY. I don't know if any of you have ever written a screenplay, but it is a LONG and arduous task! It is one of the bigger jobs, along with directing, and cinematography, editing, etc.
If, however, Lucas wished to change the prequels, which he directed and wrote the SCREENPLAYS for, I would say "power to him". I hate the prequels as they are anyway, so who cares? But that's not the point. The point is, Lucas may own Star Wars (and let me remind you that the Louvre owns artworks such as the Mona Lisa, and wouldn't DARE change them), but he did not create the OT single-handedly despite the way he talks in featurettes, and therefore it is not entirely his 'artwork' so to speak. So while the fact that he owns it may allow him legally to change whatever he wants about the OT, I do not believe that he has the right to. I do, however, believe he has the right to change the PT, as he owns, directed, and wrote the screenplays for them.