Because every thing made by Jehovahs witnesses is so shoddily made its bound to collapse. Our kingdom hall was falling apart all the time.
Wow, this really made me think of the Kingdom Hell I attended back in the early 90's when I was a teenager. The hall was built in 1974, just one year before Armageddon came. Heck, I don't think a year went by when something structurally significant wasn't happening to that building. Just shows what can happen when you put your faith in a bunch of false prophecies.
BTW, that building ended up lasting the congregation over 20 years, until it was condemned by the city...