Great thread. I, myself have come to the same conclusion. Sin is little more than a definition of "badness" or "evil" within a religious context, and most certainly is used as a control mechanism.
We learn what real "good" and "bad" is through social development. I believe this is the very reason we all have left the jws, to begin with. We saw through the thinly disguised definitions of sin, as the control mechanism that it is. The greater good was almost never accomplished because of this human definition. Eventually, we figured out the the definition of "sin" that we were taught to believe and real principles of good and bad were not in fact, the same thing.
j