Welcome to the forum. I have been out a long time, fifteen years, so I don't have any idea what is going on with individuals in the organization, but it wouldn't surprise me if many are having doubts like what you are seeing. I also think it could be a regional thing, as I live in California and in my experience JWs were different than JWs in more conservative states.
I think many JWs are in a state of cognitive dissonance. On one level they still believe, but they also see and believe things that contradict those beliefs. One indication that a person has a faith that is weakening is their zeal in the field ministry. Supposedly this is life saving work, a core belief and a requirement to be approved by God and live through Armageddon. If a JW does a token hour or two on Saturday, and most of that spent knocking at the doors of empty houses, driving around or on coffee breaks, then that is a indicator that they actually don't believe everything taught by the Watchtower. I think most JWs fall into this category.
I think they stay because they still believe it's a good way of life, they don't want to loose family, they don't like change or some combination of those things. A person could go on for quite a while in a state of cognitive dissonance, coasting along as a JW. It's only when they reach a crisis point for some reason that they may be motivated to leave. Either the cognitive dissonance becomes to much, or they are mistreated by the elders or other witnesses, or some other life crisis.