Definetly about control and not trusting that individuals know how to conduct themselves without being monitored. As is always the case with JW's , It's not enough that one attends meetings, reads the literature and applies the counsel in ones life as one sees fit. It's about small minded uneducated individuals who've been given the authority or have taken it upon themselves to enforce, monitor and generally intervene in peoples personal relationship with god.
I went to a congregation once where the P.O. wasn't happy with the teenagers level of participation during the meetings so he made all of them sit in the first few rows on Sunday. He'd assign each one of them a paragraph or two to answer during the previous Watchtower study and they were to have it prepared when he called on them the following week. This went on for some time until the teenagers all decided to get up after the public talk and go have their own Watchtower study at one of their houses. One young brother went from 19 years old to 20 years old in this time period. He sat in a regular seat one Sunday after he turned 20 and the usher came back and told him to move up front. This brother flatly refused and kicked up a fuss during the meeting.
Eventually the parents put a stop to it all but had to have their teens sit by them instead of with their friends during the meeting.
This same P.O would also sit behind the young brothers and observe their hair length. If their hair was getting anywhere near their ears, he'd lean forward, tap them on the shoulder and whisper "get a haircut or I'm pulling your publishers card". Once again the parents kicked up a fuss once the young brothers began saying "fine....go ahead and pull it".
This guy and the elders under him came to be known as the "Gestapo Crew" and people started leaving the Congregation (including my family) and attending the other congregation that met there or the one in the next town.
For some people with anxiety, it's a comfort knowing the back room is available should they start feeling overwhelmed, same thing for people with small childeren. Also for those who find themselves running late, they go ahead and attend the meeting knowing that they can just duck into the back room without disturbing anyone. Without that option, they might decide to stay home.