There was a time when the conservative end of the political spectrum was a party of big ideas.  Whether or not you agreed with Barry Goldwater, he had a theory and an idea that was unique and drove it into the legacy of a party.  When Reagan deregulated the airlines, he was acting on Goldwater's ideas.  When he cut top tax rates, he was acting on Laffer curve ideas.  Regardless of what one thinks about these things, they were ideas.  During that same period (60s - 80s), I agree with your point that the left spent more time complaining about how things were and less on how things could be.  Gross oversimplifications, I will grant you, but I think that this is broadly in agreement with your point.

However, I don't think we should necessarily give the left a pass on environmental issues today.  There remains throughout much of the left a innate  wariness of profit-seeking behavior that significantly limits the left's ability to engage on environmental issues.  Too much of the left framing is in the form of "the environment is too important to worry about economic costs" which - even where true - implicitly fails to conceive of a set of actions that would benefit both (or, God forbid, harm both, for which examples abound).  We see much of this on Grist, such as where people have argued that lower energy costs are to be avoided because they will only galvanize greater energy use.  

The right is no better, with "the social benefits of economic growth are far more important than those crazy patchouli-stinking hippies realize" also framing the debate as a zero-sum game.  But to the extent that Gingrich is making the point that there is a middle ground that the right could claim on this issue, I don't disagree (and no, I haven't read the book).  But this is equally true of the left.  From either direction though, the center is emptier than I think you give it credit for.