I agree now as its Vaders not Lukes story now it certainly weakens ANH, I hear P.T fans cristise ANH because it doesnt move the story of Vader along and they feel is the weakest Episode in the saga, as he is just the villian of the story, in ANH, and you can tell in ANH it was story of Luke as it was the concept of a simple farmboy who became a hero that was being told.