Why Internships?

http://www.youtern.com/thesavvyintern/index.php/2012/07/23/survey-75-of-employers-want-candidates-with-relevant-experience/

You've read or heard that internships can help you get a job once you leave college. You've even found out that internships help you substitute for the dreaded "previous experience required" notation in a position description.

But why is experience required? What will an internship get you that you don't already have, either in the way of skills or credentials? 

The above link is a good, succinct overview of the intangibles employers expect you to acquire. It's not so much about hard skills as it is about soft skills--knowing how to interact with other people in the business world so that you're a seamless fit.