I agree that there is a large percentage of Dubs have issues with some of the Watchtower beliefs.
From personal experience i can tell you that most of these, once reaching this stage of dissonance, look around at other religious groups and see no real alternative, so they figure this is probably still the truth.
I went through this period as well. I could see the issues, but i kept asking myself " which other religion is better?", and i simply coudn't see anything better, so i stayed. It is only when you realize that no organized religion is the truth, that you take the next step.
Even when debating with current JWs about issues, the usually reply starts with "Yeah, but..." . This "Yeah, but..." is very significant, as it implies that there is agreement in identifying there are issues, while noticing lack of alternatives. Things like:
"Yeah, but don't you think Jehovah has to have an organized group on earth?", or " Yeah, but if Jehovah can deal with those issues, why can't you?", or "Yeah, but we are sure Jehovah will resolve that in due time" are typical when a Jehovah Witness has no choice but to admit the glaring error in Watchtower beliefs.