"For example, the Bible condemns fornication and other morally reproachable matters."
First point, what the bible condemns is a moot point. Read the old testament, it condones all sorts of murderous, vile, morally revolting behaviours, including killing children. Ironically the Watchtower also condones the murder of children so we can see what sort of morality one can construct from "the bible"....
Having said that, the Watchtower sets up their own twisted moral universe where even masturbation, dating without a "chaperone", smoking, voting, having a x-mas tree, is considered morally reproachable behaviour.
I seriously doubt most people leave in order to gain freedom from these absurd "moral" prohibitions (although they would be justified in doing so)....rather, they leave once the cognitive dissonance becomes so overwhelming, they can no longer deny their logic telling them that the dictates of the borganization are complete nonsense.