I could be wrong here as I don't fully understand the complexities of the student loan system, but if student loans are anything like sub-prime mortgages, the point of the loan is not that a student should repay them. Having students in a lifetime of debt creates other commercial opportunities for those who have control of the loans. Banks and/or other financial institutions could repackage the debt, turn them in to derivatives and securities and sell it on in financial markets at an increased value to make a profit.
This of course doesn't change the fundamental value of the original debt, so it feeds into unsustainable speculation that will eventually lead to a crash. And having an entire generation perpetually in debt is an effective method of social control, as it's the same thing the west does to third world countries. The idea of student's "investing" in their future is just marketing spin to sell a bad idea to the general public, the same as promising the "american dream" of borrowing a mortgage so anyone can own your own home.
...but when the financial system realises the game is up and that student loans are practically worthless because there is an entire generation that can't afford to repay them, the banks will start screaming they are "too big to fail" and will ask the government to write off the loans anyway in a bailout package that will cost the tax payer billions or even trillions of dollars.
This is not "radical left wing" thinking. It's the difference between whether the government would rather wait for a global financial crisis to help the banks later, or help the students now. As the tax payer, you are screwed either way because the system is corrupt and broken by design and the government will take your money no matter what you do.
And before that happens, the loans get written off anyway.
Am I wrong? Anyone more informed than me is welcome to jump in...
After a quick google search, it looks (regrettably) like I'm in the right area:
How the two debt crises compare
fingfx.thomsonreuters.com