That chart shows some rapid growth around the time that society became more accepting of women in the work force. I suspect the massive shift in the supply of labor contributed to wage stagnation. Where there are suddenly a lot more college grads looking for professional jobs, you don't need to pay as much, especially given the large gender wage gap at the time.
I also suspect the increased prevelance of luxury goods is a contributing factor. Before we needed two cars, multiple TVs, video game consoles, computers, internet, portable computers, iPods, cell phones for the entire family, and tablets, people could build savings. Larger savings meant higher down payments on cars and houses and less money lost on interest payments, not to mention earning interest on the savings. Now the middle class takes their money and gives it right back to the corporations instead of using it to build wealth.
Finally, it feels like there is increased incorporation. The manager of "local bank" made lots of money. The same person still makes lots of money as the manager of the local branch of BoA, but now he has a boss at the corporate office that makes way more money, leaving less available for non-exec wages.