You're absolutely right, and I have no reasonable explanation for why I feel that way about hearing/seeing John but not Otis. The best I can do is to say that people die in plane crashes, and it's every bit as tragic, but John's murder was just so...senseless. And it came at a time when he seemed to have gotten his life together and been happier than he had been in years. I think that photo of John with his murderer hours before his death also impacts my feeling on it, making it seem even more unfair.
Like I said, not necessarily logical, but John's death, and then seeing him all full of life on video, still makes me impossibly sad in a way that the others don't.