Appropriate Work-Place Attitude: The main reason that I want the people I hire to have experience is that they already know the difference between a workplace and a night club. Nearly every kid I've hired fresh out of college still has the "party attitude" and does not quite understand that they were hired to work and not socialize. Those that dig right in and get to work have been those that have held down jobs since high school.
Secondarily, they already know that what they learned from their school books and their woo-woo instructors does not necessarily apply to the real world. As they say, "In theory, there is no difference between theory and practice, but in reality there is." Those with little or no practical experience, but with a lot of book-learning, can only learn this from experience.