Mind you--people in Japan are very smart. Science/math education is way better than in the US. But in the end, emphasis is on conformity and "not standing out too much" or "being different". This kills the spirit of innovation. I grew up in Japan but went to college in the US and work in NYC. Every time I go home, I feel like an outsider even though I spent 18 years of my life there.
My understanding is the issue here isn't that women are supposed to get married, rather that they're supposed to drop out of the workforce immediately thereafter. With a country short of young workers, this is problematic.
Again I love the culture of Japan, but much of the inter-dependence that makes it fascinating also promotes working for large companies rather doing ones own thing.