Why should people work so hard all the time? In the US, we are already insanely productive compared to almost every other worker in every other country and even compared to ourselves a few decades ago.
We work hard to bring value to our employer who wouldn't waste a minute for sympathy when they lay us off to increase their margins for a quarter, but you feel that we have to be productive all the time or else, what? We are immoral?
I contend that the worker owes nothing but fulfilling their job description. If you don't have work to do, then why find it?
There is no need to 'be productive' every working hour of every day if you don't have to be. To do so is insanity in my opinion. Go be with your family. Kids grow up way too fast and you are missing it.
Edit: I also want to be clear that I don't really think about productivity as an instantaneous measure, but more of an average over time. Someone (at home or at work) who is "coasting" in my opinion is someone who is rarely, if ever, productive. Someone who is productive is someone who gets good work done every week or month or whatever unit of time is relevant to the job at hand. What you do with this 5 minutes or that hour isn't really as important, IMO.
I agree with them. To me it isn't about the color of one's collar or the location they work from. It is about being productive. Productive workers should have flexibility, where possible. Unproductive ones shouldn't.