The OP letter is well put together and hits hard.
Alternately, a current JW who wants to disengage the religion can write a short letter to local elders stating the following:
This letter is to inform that several things about the Christian Congregation of Jehovah's Witnesses (a subsidiary corporation used by the Watch Tower Bible and Tract Society of Pennsylvania, the Watchtower Bible and Tract Society of New York, and the Governing Body of Jehovah's Witnesses as expressed in each of these organization's legal charters) have come to plague my Bible-trained conscience to a point where I'm very uncomfortable engaging in activities organized by it such as attending meetings at a Kingdom Hall, assembly or convention, or engaging in its public outreach work.
For the foreseeable future I do not wish to be approached by any authority appointed by one of the aforementioned entities carrying out their duties in that capacity. Personal social approach is always welcomed and appreciated. But, again, I do not want to be further burdened by coercion from these organization's appointed authorities acting in that capacity. I've shared my views with the aforementioned organizations. If they want they will share my concerns with you. That is up to them. It is not my intention to resist anything or anyone, except where I'm compelled by moral, ethical and legal standards I was raised and taught to embrace as my own and that are or should be well known to each of you.
I have not stopped following Jesus and have not stopped loving all of you. When I meet any of you in public or private I'll always welcome the opportunity to offer encouragement or otherwise interact as love compels me. My pray is that the several troublesome things I've learned about the aforementioned organizations from the aforementioned organizations are dealt with and changed. I'll watch for these changes, and if they occur I'll then reconsider engaging in their organized activities. Until then, as David responded to Saul when he implored David to "Come back," I am compelled to proceed on my way and leave the many troublesome things I see for God to deal with.--(See 1 Samuel 26:21-25)