As a dedicated cruciverbalist, I often run into the word 'olio,' which might be defined as a mishmash — a good definition for the thinking behind this article. There are so many unconsidered factors that trying make it jibe with reality is a stretch. I haven't got much time, so here are just a couple.
Regardless of GDP or productivity rates (which in any event are as dependent on the level of technology as anything else), big unions (in the US at least) allowed many — especially those with lesser educations — to make a decent middle-class living. The death of unions was coupled with automation and off-shoring and led to a mass decline in living standards. Look at Detroit. Who, ultimately, didn't suffer? The top 10% and even more so, the top 1%. Here, they like to fancy themselves job-creators and makers, but given that actual labor and production is done by someone else, you could as easily think them economic vampires, and (with regard to automation and off-shoring) job-craters. Real wages for most have not increased in 40 years.
Speaking of technology, remember that computers started as a means for better artillery calculation — surely a wartime advance. One needn't look too far to see how that blossomed into a productivity engine.
Then we have the matter of standard of living. Lots of things are better. In the forties, no one had a TV nor a Cuisinart nor any of a thousand other advances. It's easy to make the case that social factors have declined — families have disintegrated, in many places children no longer are familiar with nature, neighborhoods are vastly in decline, along with the support groups they fostered, (suggest reading: Bowling Alone: The Collapse and Revival of American Community <http://www.amazon.com/Bowling-Alone-Collapse-American-Community/dp/0743203046/ref=sr_1_1?s=books&ie=UTF8&qid=1419181527&sr=1-1&keywords=bowling+alone+the+collapse+and+revival+of+american+community>) Medical care and knowledge has surely advanced. On that score (again in the US) medical care is the largest cause of bankruptcy. BigPhRMA provides these miracles at an unaffordable cost. Look at the cost of early AIDS medication or more recently, Gilead Sciences hepatitis cure.
Worldwide, where once poor backward countries were the rule, now everyone aspires to the American lifestyle. There are matters of competition, supply and demand to consider, now over a MUCH larger base. One hundred yeas ago, world population was about 1 billion, and that largely rural. Today, it's pushing 7 billion from one side or the other and most are urban. Economic stresses from this alone make me goggle.
OK, out of time, so one last technical point — when you try to compare rates over time periods, it's misleading to lay a 26 year period against an array of 6—10 year periods. Go read "How to Lie with Statistics' <http://www.amazon.com/How-Lie-Statistics-Darrell-Huff/dp/0393310728/ref=sr_1_1?s=books&ie=UTF8&qid=1419181214&sr=1-1&keywords=how+to+lie+with+statistics>