I don't think commenting will ever be stopped - it's a control / personal reinforcement learning mechanism ( a bit like the "personal testimony - why we believe the Mormon church is true etc" in the LDS).
For many years we had a really good "old school" WT conductor who made it a genuine bible study (within the limited parameters of the article) and he encouraged additional research and commended answers that weren't basically cut and paste verbatim from the paragraph. It was a real highlight , to be honest , and probably kept me in the Org for an extra couple of years , in hindsight. Sadly there was an elders school that focused on "sticking to the material" and I think he got privately criticised by a CO so in a shake-up of elders duties he decided to resign taking the WT feeling he had done it for long enough and wanted to give a younger elder the chance. The new guy was pretty useless.
Sadly real teachers like that are few and far between in the Society these days and the religion is so "dumbed down" that most people just regurgitate what they read in the paragraph.