I think OS and their GUI's are in a fine place. People have been using file/window based computing for many decades now and it would be hard for any large change to that paradigm to take root.

Most everyone here on HN should be considered a power user and are in the minority of personal computing users statistically. A good idea is to give people options to configure things how they like so power users can feel more powerful. I think the reality is most people fool themselves with any perceived productivity benefit on window/screen management - its just a comfort feeling more than productivity. If people truly wanted to be more productive they'd spend less time on internet forums :D