Independent has many different and new meanings. Those who consider themselves independent and on there own cannot truly be on their own as they receive help from a variety of sources. The American image of leaving the nest after college was popularized with the times and situation of post WW2, when the young went to war and were seen as having made it, grown up, successful and for the most part "Manly".
Skip ahead 20 years and the standard for a "family" was out of the house by 18-25, married in a year, children within 5 years, mortgage on a house by 27...whether you wanted it or not that was life. If you didn't want it? You hide it and probably did it anyway. Society pressured you into it and whether it was right or wrong it was done. Many people who grew up in that time are now discovering that is not who they were, not what they wanted and feel saddened, depressed and angry. Those who did want it may even look around and see that there were other was to go about getting it..