So you believe an agrarian and an informational society place equal demands on its maturing citizens? Are you asserting that early seventeenth agricultural society. for example, demanded the same preparation for assuming one's responsibilities as this 21st century informational one? All the extended preparation for a career isn't the main factor in the delay in marriage? Kids starting at what, 16 or so should go out in the world, get married, begin a family, perform the necessary work to support said family, AND attend classes?
Are you assuming that economic exigencies can trump human nature? I have to tell you, human nature is always going to win out. Our economy and educational system have to accomodate themselves to the fact that people are better served by remaining chaste (no sex before marriage; fidelity afterwards), and that it is unreasonable to delay marriage until the late 20's or 30's.
The economy exists to serve human beings -- essentially to support families -- not the other way around.