Myself, I'm kind of mixed on the supposed Qui-Gon scene from ROTS. Sure it would be cool to hear him. But, looking at the scene, I believe it was wise for them not to do it. As it is, the scene is very quiet, and the camera pans around Yoda's head before Bail Organa walks in and announces that Obi-Wan has made contact. You can tell Yoda is meditating or something, but you don't know exactly on what. And then later on, when Yoda tells Obi-Wan of his communication with Qui-Gon, it has an element of surprise to it as it is. I believe that's why they left the voiceover out, because of the surprise to the viewer when they hear Yoda tell Obi-Wan of Qui-Gon. I like it this way. However, as I said, I think it's cool to hear Liam again as Qui-GHon, so they could have at least had Liam record it for a deleted scene.