The trend suggests that the pace of productivity growth has decelerated since the first half of the 2000s. That begs an important question that the robots-are-coming advocates need to answer: Why a phenomenon that should be associated with accelerating productivity is allegedly occurring over a fairly protracted period where the [productivity] trend in output per hour is going the other way?
My own take. We’re still coming out of a severe macroeconomic down cycle, the credit crisis, deleveraging, and the liquidity trap. The prevailing pessimistic economic theories — the death of innovation, the crisis of inequality and yes, robots eating all the jobs — will fade with recovery.
(For bonus points, identify the other tech-driven economic force that could explain low productivity at a time of great tech advancement. My nomination — tech-driven price deflation lowers prices, reduces measured GDP and productivity, while boosting consumer welfare.)