Well, yes, but... most letters that are published are those that already have an answer that they would like to drive home. That would not be honest. Why are the letters questioning the UN association not published? Why are there no apologies for the publications made regarding the pre-1975 enviroment? Is there a need for someone to point them out?
I attended the international convention of 2014 in Houston (spanish). An example of a "doubter" was presented. A pioneer from Argentina was interviewed regarding the new light. it went something like this...
Speaker - Here we have a brother that has seen Jehovah's hand in providing new light.. Brother, tell us about your questions.
Brother - I have always had a pondering questions in my mind. How could it be possible that the 144.000 were part of the slave class and how could they possibly be of any help if they are so far from the GB. Well, the new light on the GB brings about the answer to this question. The GB IS the faithful and discrete slave. This makes much more sense now.
Speaker - Thank you brother. Your example shows how Jehovah always answers our questions.
True Story.
I guess what we need to see is an example where a number of letters written to Brooklyn has brought about change and much more specially, were the organization has admitted that the input from the brothers was instrumental in bringing about change.