Most baptisms in the USA are from born-ins who also have the lowest retention rate (same problem for the Mormons though not as bad as the JW's).
Perhaps these born-ins have seen the devastating results of getting baptized and then making a mistake, even a very minor mistake by worldly standards and have seen how nasty it can get for the baptized person being shunned by family and friends.
Being an unbaptized publisher allows one the social life.......... the only real perk the JW's can offer........... but without the danger of being shunned.