Interviews are tough. There's very little time to get a feel for whether a person would be a good fit for an organization - and often, you have to make a judgment: was this comment just off-the-cuff curiosity, or does the fact that the person brought up the open-plan indicate that he or she would have problems with the way that the company works?

In interviews, the open-plan office is non-negotiable. It's not like you're going to convince them in an interview to change their minds and build closed offices. I can imagine a lot of interviewers going "well, if he or she brought it up and has actually studied literature on it, then it's probably something that bothers them, and if it's something that bothers them, we might have a problem down the road... maybe it's better to test the water than to offer full employment."

To be clear, this is a problem with the interview process, not with you (or the person hiring). There's just not enough time to actually understand a person, so interviewers are forced to make guesses and go with their hunches. And because the cost of hiring the wrong person is high, interviewers will often look for any small thing to refuse a hire.