Justin,
I think you make a very valid point as to why the JW's are generally so spiritually unfulfilled. For the first time ever, I think, I disagree somewhat with Narkissos' post.
Whoever lives in a subculture knows that there is a wider world around and has to use different sets of codes and references. As JWs we didn't speak and behave with "worldly people" as we did with other JWs. Which means that we were conscious of the main culture and able to adapt to it (although awkwardly sometimes): we actually belonged to it too .
This opinion is only from my personal experience and from examining JW's since I have been out. But I feel that while we (JW's) are somewhat conscious of the "main" culture, our firm belief that our "subculture" is absolutely correct does not even make us fully capable of belonging to the "main" culture. The "main" culture exists only to prove more fully that our "subculture" is correct.
My point is that, although, in essense we did of course exist within this "main" culture, the complete lack of acknowledgement of any good coming from it, is what has created such unhappy, dysfunctional human beings who are/were JW's.
By the way, I'm in the line with those dysfunctional ex-JW's.... I figured out the happiness part.... but integrating "normally" with the "main" culture is not quite so easy. teehee
Brad