Being involved in the Slow Food movement I also see the inspiration for slow productivity.
But I can't agree with the negative, somewhat fatalistic point of view.
I believe we need voices like Newport to someday be heard by people at the top running companies that are plagued by middle (project) managers that need to be seen as doing something.
I have seen the value of great client and project management first hand (albeit these were far and few). And I have seen the productivity it provided for the teams involved by providing goals, guidance and a map as well as trust and keeping distractions away as best as possible.
And I have seen busywork, work simulation and the simulacrum of work.
I value uninterrupted time to get stuff done. And I learned to be okay with days filled with meetings that also pay the rent. I know what I enjoy most, though.