When I am reading a fictional story or watching a film I enjoy the voice of the narrator as a mysterious presence. If the voice educates me, I feel involved and am not concerned about whose voice it is.
I think it is the author's decision however and I think it also depends on the subject. If they want to discuss their work online for educational purposes I think it is a useful resource however if they want to discuss autobiographical information for the reader I feel it isn't necessary.
If a non-fictional writer has published a pioneering piece of work on a particular subject however; I think it is important for others in the same field to meet and assess the new theory and also give them the recognition and appreciation they deserve.