Sparrowdown...
I agree that questioning the underlying faith (or lack of it) is of importance and that this cannot be quantified and therefore visualised, however I think that the graphs do have several important purposes.
They do show clear trends for any that wish to argue that the WTS has enjoyed unbridled growth. They expose the cherry picked figures that the WTS bring up (e.g. number of publications, number of hours, numbers baptised each day) and bring context to these. For anyone starting to wake up they provide compelling evidence that not all is hunkydory in WT land. In addition they provide support for hypothesis about the reasons for the less than altruistic actions of the WTS in asset grabbing.