There needs to be a place for people to work in peace. Not every project can be solved with collaboration. The work culture in America strives more for team building, but you do not always need a team to accomplish a task. Sometimes, just working in a cubicle does not offer enough peace and quiet.
Yes, there should be more spaces at work for solitude, not just for collaboration, because a lot of times, people have to do work that requires them to concentrate. If a person has to write or develop policy, they need to be able to relax and think. This requires space to think without interruption.
One of my biggest frustrations at work is the fact that my desk is located in the middle of the office, with no privacy whatsoever. Being in this position makes it very easy to interact with other people, which can be a good thing - but can also be incredibly distracting. I would be a much more efficient employee if I had a space where I could just get my work done without any distractions.
Yes, work places should allow and provide their employees with their own private areas in which to work, in addition to the current work space designs that typically feature collaboration areas like conference rooms. Workplaces shifted over recent decades to favor open spaces in which employees could collaborate, but workers need to be provided with quiet, private areas as well.
I personally agree, I agree with you; your words 'Clearly workers need longer stretches of solitude to create and think, to be more productive' - to my mind, are very right. I've read an article about some scientists saying that open work spaces 'damage' our minds and simply do not get our brains concentrated.
But is it not, in many cases, simply less expensive to create an open office rather than a room for each?..