I think there are a number of factors going on here, one of the biggest being the theoretically-ended recession and, more critically, the continuing high rate of unemployment. When graduates enter a job market with high unemployment (especially for lower-end and entry level jobs), it makes it nearly impossible to them to establish independence. Many are forced to move back home or otherwise live off of their parents income. Given high unemployment, it seems nearly inevitable that this is going to happen to a sizable slice of graduates. Hence, I think it's important not to read too much into character of 20-sometings given the economic realities.
Of course, that's never stopped people before... so why should it stop me?
Another thing that seems different about middle class and upper-middle class 20-somethings today is that many seem to have had incredibly managed childhoods compared to people of my generation (Generation X). In a way, it seems like young adults of today never had the kind of sprawling, relaxed free time that characterized much of my childhood. Instead, they were ferried around to soccer, music lessons, tutoring and other managed activities. From the outside, it seems to me like many of these kids were being pressured to succeed and groomed to get into the right kind of schools from a disturbingly young age. It also seems like all the programs and activities and worries about child safety would reinforce a message of "your life and well-being importance to the adults around you" and "follow the programs you are given and you will be on the path to success."
So, by comparison it looks like today's young 20-somethings have had more directed lives and less self-automony than we had. Activities and schedules were often provided them, with a parent waiting to swoop in should anything go wrong. It seems like some kids in that environment get very little practice being self-directed.
I have to wonder if having lived such a programmed life for so long, that people graduating into the work force today may feel overwhelmed by the sudden lack of structure and the multiplicity of options. I wonder if they feel subtly betrayed that they jumped through hoops during their over-scheduled extracurricular activities for years, and now suddenly there's no obvious hoop to jump through and all that work doesn't appear to be paying off.
Before the downturn there was a lot of talk about how "entitled" young people entering the workforce were (which would make some sense, given their over-programmed childhoods). Now those entering the workforce are dealing with other issues, including having to deal with suddenly diminished expectations. That's never fun for anyone.
Now, granted most of the above only applies to a subset of middle and upper-middle class 20-somethings in the US, but I do think there have been pretty big changes in attitudes towards children and how children's lives are scheduled.