People do the open office floor plan because it's efficient and economical, not because it's the the best for the workers.

We designed a ton of cubbies (like in your university library), 1 person private rooms, 2 person conference rooms, etc. in our office to accommodate for the fact that many people need to more privacy and quiet than just headphones. We also break up the main open plans to help quiet the noise and distraction.

We have about 45,000 sq. ft today, and will be adding another 45,000 sq. ft this year. When we do, there will be much less open floor plan. I do think there's a happy medium, with team rooms of 6 to 15 people, depending on role and requirements.