I think it's very much workplace-centric. The new manager who implemented this open office system came from a commodity sales background, so having all of these salespeople in the same room increased communication efficiency.
However, this workplace is not in sales. We are much more on the regulatory side, which means we're dealing with private information. Previously we did a pretty good job of maintaining information security by compartmentalizing issues to those individuals who needed to know.
Now, although still handcuffed by the same privacy legislation, we're expected to have these private conversations beside each other in a single room. How comfortable is the person on the phone going to feel about releasing private information if they can overhear everyone else's conversation in the background?
Again, I reiterate that these people aren't leaving because of the open office space concept. Removing all of the walls in the office just happened to also remove any reason to stick it out and try to work through the other problems.