I think most people acknowledge that the world is not the way it is supposed to be. Thus, the question "why" is born.
I'm not entirely sure that the world is supposed to be any way. It just is.
You are right about depression/suicide rates in the West, but I don't know whether you can show causality between that and a lack of spirituality, per se.
After all, I don't think it's been shown that poverty-stricken third world people are necessarily more philosophical or spiritual, yet studies seem to indicate that they are generally happier, even though their lives are shorter and can be filled with loss and pain.
My own sense is that the depression that many feel in modern society may be caused by a number of possible factors that may work in combination.
One factor is the fragmentation of social groups and the emphasis we place on the primacy of the individual - I think that can be quite isolating.
Another might be our cultural priorities and definitions of what constitutes success combined with the idea that anyone can be professionally and socially mobile. These priorities and fluidity has been amazingly successful for innovation and business, but possibly damaging in its affect on those who have not achieved what they believe to be their potential.
This is encapsulated in the ideal of the American dream, an ideal with some truth to it but perhaps not as much as popular culture invests in it. Yes, you can bootstrap yourself but it can be more work than many are willing to put in or could even be beyond their abilities.
Then, combined with the hugely increased leisure time that industrialization has brought when compared to our forebears, and an education system that necessarily focuses on practical learning rather than on philosophical, personal or spiritual development, and you have a problem of fulfillment and you may not have the psychological and critical tools to figure out a solution.
If you're not struggling to eke out a living, and you have a lot more time to think, plus you're not supported by a closely knit extended family or society, and you feel like you've failed to achieve attainable goals, then that's a recipe for trouble.
It is also even possible that our desire to cushion ourselves from the pains and discomforts that life inevitably brings may weaken our self-reliance and inner reserves when we are confronted with these existential questions.
There is also the possibility that environmental factors, such as high-fat/processed sugar-rich diets may also affect our psychological wellbeing.
