Regardless of how it comes about, youthful dislocation does seem to be a common trait among authors. I remember some research discussed in Jonathan Franzen's book, How to Be Alone, which demonstrated that alienated adolescents often turn to books and writing to supplement the social interactions they don't have. I imagine isolation is also good for tuning a person's critical eye, the ability to calmly watch life and assess from the sidelines, something at which many good authors are extremely adept.
Way to save face for us hopeless lit geeks!
(This thoughtful post of Scott's is actually about Ian McEwan and cultural exchange. Nevermind me.)