Hi Cold Steel,
You've posted a fair bit of material. If I get more time, I'll read it and respond. Here is a couple off the cuff comments...
"And I understand why. Any person leaving any church in bitterness feels that they’ve been manipulated, deceived, and that they’ve wasted a lot of time for nothing. That’s why many become atheists."
Indeed is not a nice feeling to make the awful discovery that a trusted source has in fact been less than honest. However, for what is worth, in my own case, I generally felt fairly positive about my involvement with the Witnesses, especially during my younger years, where I was adopted by the congregation as a "fatherless boy." Since both my parents were disfellowshipped, I went to meetings alone, even as an 8-year-old. I also remained in the faith for several years, after admitting to myself I was an atheist. At the time, I would have not expressed it so bluntly -- probably more of "I have doubts about the existence of God."
One Ex-Mormon in particular impressed me with how he expressed his feelings. His story convinced me there is kinship between Mormons and Witnesses who eventually come face to face with their doubts about the veracity of their faith. I found his story on exmormon.org and recall his concerns about DNA vs faith claims regarding American Indians. My point here is not the focus on his concern, but instead how he expressed feelings that were akin to my own. It has been a long while since I read his story, but I just skimmed through it again for this post.
Here is a snippet that captures his feelings: "I didn't leave the LDS Church and stop believing because it was easy. I desperately wanted the comforting teachings of the Church to be true. I don't have any brilliant insight to offer about the meaning of life, and I haven't found another true Church."
It is story #125 - Simon Southerton from Australia.
"But at the same time it’s foolish to put the Mormons in the same category as the WTBTS."
Some aspects are the similar, some are different. Naturally a believing Mormon will focus on the differences that seem to make the Mormon faith "correct." In the end, it is often a personal journey. You speculated on why many who leave the Witnesses become atheists. But of course, you don't know, right? Having never been a Witness or an atheist, all you can do is ask and draw conclusions on what may be the reasons. Likewise, although I can read The Book of Mormon and express critical vews about sections of the KJV being plagerized, this is not the same as being a Mormon. What the LDS faith means to you, would naturally go beyond such things.
Cheers,
-Randy