I believe, based on what I have seen in my wife's congregation, that JW's "childish" tales attract the naive, the misinformed, the uneducated, the forlorn, and the mentally unstable. I actually believe the religion is good for them overall. I wouln't even try to awaken them, especially if they are older. However, the part that turns me into hulk is the indoctrination of the born-in whose potential and critical thinking abilities are quelled from the very first day they step into the KH.
I think the "mental" cases in the JW congregations are of two types: the ones they appeal to and the ones they create, especially the born-ins.