Can you blame kids (especially those without siblings) wanting to strike out for a life and family of their own?

They don't choose to be born. Have few/no rights to change how they're raised or their parents spend the family funds while they are minors. Often they have no choice over large portions of their education. To say they owe their parents decades of unpaid caregiving is absurd.

I'm speaking from a Japanese cultural point of view, here. To say that Japan has been wrong until now to focus on family values over rampant individualism, waiting until you are married to leave the home, and respecting the lives of the elderly until they pass on is one I've never heard before. And where do you get that their education takes a backseat by living with their parents? Post secondary education has always been a pillar in Japan.

Until this most recent generation Japan (and the rest of the world) had no problem starting a "life and family of their own" as you put it.