I think that in the 1950's/1960's people did not have to worry about their jobs as we do today. The Bosses back then depended on certain employees to do the extra things, beyond their job descriptions. If you were an employee of the company for 20 years, showed up for work everyday and went out of your way to please the boss, YOU were a valuable employee.
Nowadays, there is no such thing as a valuable employee. The boss is out for himself and will take advantage of anyone who wants to help him get to the top. Employees who consider themselves valuable are kidding themselves. Everybody can be replaced, there is no job security in the workplace. Education and technology has made it possible for a boss to replace you with someone younger (right out of college) with the skills needed to perform the job and better. Plus, when the management decides to let you go and hire a new employee, they pay out a lower starting wage and less benefits(no seniority).
Today, with unemployment on the rise, employees should value their jobs, but keep in mind that everyone is replaceable and there are 100 people waiting at the door.