THE_RAISIN- My opinion is the WT society stopped having book studies in the private homes because they thought Witnesses were getting too close to one another. Think about it - if a JW wanted to show another JW something on a computer after a Book study, it would be possible in a home. But by restricting the Book Study to the Kingdom Hall only- the elders keep more of a monitor on individual JW's relationships in a formal setting. I think THAT is what it's about.
Actually, I think the attendance at CBS was so pathetic in many places that it was easier to end them than to try to build up attendance.
Plus, in many areas where several congs are sharing the KH, it freed up many weeknights, thus allowing another cong or two to utilize the same building instead of having to build a new structure. $$$ saved could be funnelled to "higher" priorities.
Finally, NO ONE was studying with their kids! (And everyone knows the young people are running out of the Org.) When the hell was there any time to do that? Now, it's a major guilt trip if you are not using the former CBS night for your Family Study (Worship Night). And IMHO families ARE doing it!