The trouble with productivity as a value is that it treats a morally ambiguous act as a moral good. What, specifically, do we want to be producing more of? From the perspective of the owners of and investors in commercial enterprises, so long as business is going well, more productivity is always better.
I suspect a slave mentality at work here, the transformation of the wage slavery most of us live under into a matter of principle. After all, if we choose to work like dogs and treat it as a form of self-improvement, isn't that a sort of freedom?