Appending the prefixes "under" or "over" to nouns and adjectives is mostly a rhetorical device that regularly appears in political discourse. The current example is political and journalistic analysis of the economy. First, the state of the economy is fretted over; then when recovery sets in, it is a "jobless recovery"; and now, when there are better jobs reports, these are not "good jobs" and many who are working are actually "underemployed".
Keynsian analysis or labor market search models can explain underemployment as well as they can explain unemployment. Yet, this is not what the political discussion is all about. Rather, it conjures vague and nefarious schemes.
Time to go back to Occam's Razor and Father Guido Sarducci who reminded those who may have forgetten that, "there's a supply and there's a demand". It even works in labor markets. The "good jobs" have a way of finding trained people. Those who are less productive can complain about the market wage that prevails in their own highest and best use but that does little good.
What makes the demogogery so unpalatable is the fact that so many young people are so poorly trained these days -- and that this sad state need not be addressed if enough people believe that one can catch "underemployment" mysteriously, somewhat like catching the flu.