I regarded my MBA classes as semester-long courses in applied critical thinking. There were few right answers although there were those which clearly were wrong. At no point did any professor say, "Make business decisions based on the values of these metrics."

A good analogy might be found in some software I'm working on now. Part of it is a specialized serialization scheme designed to produce small serialized forms of large numbers of similar tree graphs. It is easy to quantify the size of the serialized form of N million trees, and it is easy to measure the CPU/IO time required to produce this form. However, when making design decisions, I only use these metrics as one input into my thought process. If I do X, how easy will it be for others to maintain after I leave (I'm a contractor)? Does a proposed design decision limit future opportunities for this module's use? Does "brittleness" increase? Does this decision move the design further away from using Mongo/HBase/whatever in the future, or does it lessen the current impedance mismatch? The easy metrics are time and space, but the might not be the most important ones.