Lurk,
I think you nailed it; I believe that the WTBTS does become attractive, not so much to a specific person, but people who, ( and we have all been there) are at some point in their life vulnerable or are looking for something, or trying to make sense of something; or need additional structure to cliing to.
It takes hold violently with some, and slower with others. In my eperiences, if people are level headed and secure in their lives, they have no need for those "fundamental " beliefs. If I have offended some with that statement, I do apologize. Some people were raised with the faith and had no choice. There are people who are secure in their beliefs as JWs, and I wish them well--fortunately we live in a time and place where you have the freedom to worship as you please.