I think this plays a LARGE part in these stats. I have two sons, 27 & 25. The oldest has a finance degree and a decent job at a local bank. Still though, it was only about a year ago that he was earning enough, and had saved enough to move out on his own.
He's getting married later this year to a very traditional young lady of the same age. I think, he would GLADLY have moved out and married several years ago... if he'd been earning more money.
The degree to which someone wants to get married is directly proportional to how bad looking they are! The better looking, the less of a hurry.
The middle class is gone. In past generations, your son would have been happy to move out with that job into a house or neighborhood he could afford. Now they are all slums. True, traditional middle-class neighborhoods are few and far between these day. My parents gave me the boot with no option to live at home so I did live in the slums for about 4-5 years. Definitely motivated me to do better, but I can understand someone not making the choice to do the same.