I think if you went to that watchtower study you would be majorly disappointed by the reaction. There won't be one.
I am not convinced this is even a change. As far back as I remember they have always held two contradictory positions.
For the most part they uphold the line that they are jehovah channel, spirit directed mouthpiece. This is their position of strength.
However when it suits their purposes -when they make a mistake about prophecy they roll over on their back and use the 'we are imperfect men' line. I can't remember the exact wording of their 1975 non apology but wasn't that what they said? They don't tend to use this defence often as it takes away their power but it is in their historical arsenal.
Witnesses are able to accept both positions and not recognise the contradiction.
As for why they are using this 'we are just imperfect humans' argument now, I agree, I can't see a reason for it other than to lay the groundwork for changes in the future. This is like an apology for something that they haven't announced yet.