Witten's paper, mentioned in the previous post, still touches me. The paper is written by an excellent mathematical physicist. His and the paper's story is the story of a man that enters a maze, sent by many people who trust in his abilities. But instead of looking for the exit, he remains enamoured with what he find in the hallways. In a dead end, he finds an old machine. He starts exploring his machine. After a while he understands what the machine does. He then walks back the maze along the way he entered it, and tells everybody about the machine and about what it does.
He is proud of the machine that he found, and is proud of solving the mystery of its workings. His ego swells. He is admired by thousands of people. He wins prizes.
Then a few people start asking about the exit he was supposed to find. He avoids the answer. He points to his achievements. A sense of disappointment starts to spread.

The exit of the maze is unification, the machine is string theory. String research is good for your fame and ego. But string theory is useless for unification.