This article seems to be tearing down a straw-man. I don't see people arguing that you must be in a "flow" state 100% of the time, or suggesting that all time not spent in "flow" is useless. The argument, as I've seen it, is just that when you have the opportunity to get into a flow state, it's a Good Thing, and that one should try minimize distractions (cough open plan offices cough) that are likely to keep on from being able to achieve "flow" or sustain in for useful periods of time.