This Philadelphia Inquirer story contains quotes suggesting that the problem is that students take long breaks from school and need a long while to identify their preferred path. Are today's students more likely to need these breaks than past students? (just asking) Isn't part of the problem that, as resources diminish, universities are less inclined to offer the courses needed to graduate on time?
http://www.philly.com/philly/news/new_jersey/20140922_Class_of_20___Most_freshman_need_more_than_four_years.html
http://www.philly.com/philly/news/new_jersey/20140922_Class_of_20___Most_freshman_need_more_than_four_years.html