In my experience spirituality tends to promote growth, self-awareness, responsibility...religiosity tends to promote dependence, and victimhood.
If you don't want to be responsible for how your life turns out, then religion is the answer because it tells you: 1) whatever bad is happening is not your fault and 2) someone (GOD) is coming to rescue you.
Spiritual people I know who are also religious tend to not hold extreme views of good/evil, right/wrong or to shift the blame to someone else when things don't turn out. They also don't expect that they can just sit on their hands and wait for someone else to rescue them. Instead, they promote the idea that we are all responsible for ourselves, and the community. They look for and see the good in people, and support them to be their better selves. In fact, many of them seem to hold the view that God expects you to live up to your potential.
Especially among JWs, the viewpoint that "this world is so horrible" seems to comfort them because they think the worse it gets, or the worse they perceive it to be - the closer everyone is to having things get better because God is going to wipe it all out and start over. This outlook, I think, accounts for the reason why JWs put everything on hold - I won't __________ until the New System. In the New System, I'll learn to (cook, play music, dance, etc) Understandably then, the majority of their expenditure of time, energy and focus is on "surviving" to the end.
The reason why people are't happy is that their needs aren't being met. I'm a firm believer in Maslow's Hierarchy of Needs. Look at the chart below. Most JWs function on very low levels. In fact, instead of meeting the needs of individuals, the material and organization is structured to invalidate a person's experiences, telling them that meeting their needs is wrong, and that the reason they are unhappy is because something is fundamentally wrong with them (they ARE sinful) and that this "wicked system of things" is stacked against them.
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As I was doing some research related to Maslow, I remembered the account of the Sermon on the Mount. The first thing Jesus did with that crowd was feed them. I've always wondered why he would do that. Then I saw Maslow's chart. Of course, if people's physical needs aren't met -hungry, thirsty, need to pee - they can't sustain attention to more sophisticated needs like spirituality. I don't even know if this story is true, but I think it is very insightful into human nature. If it is true, and it was put there as an instruction - it is even more telling that JWs do not follow this example in any real way - they do not have homeless shelters, food banks, etc. They blantantly ignore the example of the man they proclaim to follow.
Following the organization's lead, a person proves their Christianity by having a hard life. JWs tend to be uneducated and low skilled workers. So they are in fact working harder than people with education and skills because what they can do is less valuable to the marketplace. In this way, their perception becomes their reality. On top of that, they are trained to ignore or devalue any good that may exist in the world - what is accomplished by non-profits, individuals or evidence of basic human good. They focus on and see the bad, ignore the good.
Their need for love and belonging is meet in a community where approval is conditional based on an individual's willingness to replace their own judgment with that of another (parents, elders, the organization). Their need for safety (emotional and sometimes physical) is in jeopardy because if an individual relies on their own judgment they no longer "belong". JWs are discouraged from individuality, self-esteem, or acknowledgement of skills and talents. JWs are not allowed to pursue (at least not openly) the natural process of self-actualization.
It would be nice to see JWs be able to get to a place where they can both acknowledge and promote the good that humans do. I would like to see a system that meets the needs of everyone by doing good for others, demonstrating Christian qualities in their everyday lives to draw people - speaking to the potential they hold instead of condemning them for the wrong they do.
My burning question is: as Christians, why can't we work to accomplish the good we can while we wait for something better? Is this not the example of all the great leaders in history? Mother Theresa, Ghandi, MLK, and even Jesus?
My conclusion is that the reason people are unhappy is that JWs fail to meet the real and current needs of individuals while at the same time holding out a vague, narrow and abstract promise of the opportunity to self-actualize. People are drawn to their own potential, they just don't understand it's right in front of them, even now.