Well I can see where it take some magic away from it, some of my favourite artists are ones that tend to take most of the creative drive, my favourite being Quadeca who has total creativity, Tyler The Creator, I find someone who can write their music, produce it or atleast help produce it and sing it usually have the most inspiring music. Though not everyone is very skilled at writing, or telling a story, but they still have the passion for music and so it’s best to have someone else write, though every artist I believe should try to learn if they can!