Despite the many configurations and variations of the language used to describe it, it's the hands-on process that people who express a preference seem to be reacting to. It doesn't matter at all that there's art and craft to the digital workflow (which, of course, is the case), it's the "feel" of the analog way of making a photograph that's being spoken of. Tim Rudman says it eloquently in his "The Photographer's Toning Book", but I don't have it handy to quote from. If you have access to it, his comments about analog work are at the beginning of the first chapter I think. (A terrific book for it's intended purpose, btw.)