I think a lot of people value having other people around and in their sight, even freelancers leave their home office and head to coworking spaces and claim productivity gains. Personally I think the office per person idea is overrated, however I've worked in many places where the draw backs of open office hit sometimes. I think the best combo is open office, with hot private offices, and with the extra space, sleep rooms, relax rooms, big working table rooms, even put hipster stuff like a standing desk area in maybe etc.. Oh and if an employees ask for NC headphones just buy them! Also if someone really in the zone on something that distractions could be problematic be okay if Fred say's do you mind if I work from home today on this problem.