I am a software engineer, and that might be different than what your people are, but I am absolutely convinced there is a stronger correlation with company loyalty and privacy of workspace than realized. No I can't prove it, but I have enough evidence to convince me.
Having been in the software industry for more than a quarter century, and having worked many years with both open and private work areas, the correlation of happiness and hence loyalty to privacy are much too strong for me to ignore. Collaboration is important, but might be overrated. Daniel Pink's best-seller book "Drive: The Surprising Truth About What Motivates Us" gives evidence that individual work is what motivates people. Collaboration, while necessary, if forced and over-emphasized seems to detract from autonomy and thus motivation and ultimately loyalty. Open offices feel like forced collaboration to too many prople. And, ironically, many people may not even truly notice it - they just are not as happy in open environments and are happier with privacy, but strangely may not fully realize it as strange as it may sound. Hence the keyword "Surprising" in the title of Pink's book. Granted, I realize his book isn't really about open offices. But privacy seems to facilitate what he is talking about.
I can't ultimately prove any of this, but I have intimately paid attention to these issues throughout my career.