Federally guaranteed student loans put the federal government in charge of deciding who can and who cannot attend college. The loans are not given on the basis of financial ability to repay they are given on the basis of an interesting set of criteria that make little financial sense.
Part of the societal benefit of these loans is that they can be repaid by becoming a teacher and other several other forms of public service. This puts the federal government in the business of recruiting for these positions.
Those who do not go into public service find themselves with a large financial challenge - a set of loans that often are out of line with their working life. Some fields of study, while expensive, do not lead to lucrative careers. People in those fields will never be free of their student loan debt - their only relief will be death, or perhaps disability. This puts the federal government, in all it's benevolence, in the same position as the post-civil war plantation owner who loves his indentured workers.
State university systems for their in-state students stand the most to gain - without easy access to loans many students will be forced to choose the budget education rather than throwing caution to the winds and signing up for the much more expensive private institutions.