Noisms recently wrote a post, the gist of which was to extol the virtues of practical experience as a GM over mere technical knowledge. It can be found here.
I would tend to agree with that, but I think an even more important consideration is being overlooked.
Noisms asks the question, "who is the better DM - the person who has only been trained in the rules
or the person who knows the rules but has 10 years' experience at the
table?" He and I agree that it will likely be the person with more experience.
But an even more important question is this, "who is the better DM - the person whose total knowledge of the world and humanity comes from daytime television and trashy novels, or the person with a rich social life who is well-read in both great literature and non-fiction?" I think the answer is obvious.
But so often gamers seem to think that the game begins with prep and ends when the last hit point is expended (Alexis at Tao of D&D is a notable exception - he has often written on the importance of being a well-rounded, well-educated human to gaming, and that is one of the reasons why I have so much respect for him). So often the importance of being a good human being is ignored.
Without an understanding of politics, economics, geography, physics, meteorology, sociology, military science, etc. etc., it is very difficult to run a convincing game world. Without extensive experience of varied social interaction and without exposure to the depths of humanity present in literature, it is very difficult to run convincing NPCs (or PCs, for that matter).
One of my favourite quotes - it was said regarding musicianship, but can be applied equally well to playing D&D - is "Remember that sitting under a tree is also good for your playing." It was a reminder that beyond the technical and the practical is the human, and D&D is nothing if not a game that is deeply human.
So, get out there - read Dostoyevsky. Watch Kubrick. Experience Rodin, Mondrian, Matisse. Fall in love, argue passionately, make and lose friends.
If you want to play great games, live great lives.