I think this wanting to know everything about you is nothing more than wanting to control you. If they were to respect your privacy, you would have some rights in their regard, and this they don't want. I think this is why dictatorships make it a routine to ignore their own laws. Also, if there is something they don't know about you, then you can act in ways they cannot control. I have no doubt that it is deliberate.
Many people have pointed out that controlling your sex drive is one of the most powerful ways to control you.
I am sure you guys can see the contrast between the practice of their needing to know everything about you, even by snooping into your life, and the extreme secretiveness the Watchtower allows itself, to different degrees according to rank. For example, worldlies and even other witnesses can be deemed "not entitled to know the truth". The rank and file witness is not to know the contents of the elder's manual. So-called judicial hearings are secret, and the group of elders acting on one is answerable only to itself. Et cetera.
I have never read a comment in this sense here, but, based on my experience with mankind, I am also sure that an occasional secret is kept for future blackmail use, when the time is ripe. Or, it is kept until confirming information is obtained.
I'm sure they would claim that this is not organizational practice, but individual noseyness. But, if you are forced to interact only with people who are nosey, you become nosey yourself. One question would be, does the Watchtower encourage witnesses to respect one another's privacy? We know the answer is no.
Before I forget, in her book "Prisons we choose to live inside" (http://www.amazon.com/Prisons-We-Choose-Live-Inside/dp/B000H2MD4W/ref=sr_1_1?ie=UTF8&qid=1309362169&sr=8-1), Doris Lessing informs us that the American government was astounded to find that some of its soldiers were confessing to crimes they had not committed. They found it was the result of brainwashing, as practiced by North Korea. Then, the American government started a program of its own to study the effects of brainwashing on people. Let us remember that Robert Jay Lifton's studies had to do with the same experience.
I think this denial of privacy is a form of behavior control (you can only do as we say, and we want to know if you're complying).