No one wants to work in an open environment.
That's not what I see. Go read the article, or other articles about them. There's tons of comments from people saying how much they love working in open environments, how they love the "camaraderie", being able to ask people questions quickly, being able to overhear conversations and know what's going on, etc. Yes, there's also lots of comments from people like you and me who hate these environments, but don't make the mistake of thinking everyone is like us; clearly there's lots of people who aren't, and apparently a lot of those people have infiltrated the programming profession.
Yes, cost savings is also a factor, but it's not the only factor. There really are a lot of people who like working that way.