We are living in an Ultra-Reactionary Time when the Ruling Class doesn't just want to reassert the Dominance of Neo-Feudal Capitalism but crush the hopes of the Working Class and Middle Class.
So of course Congress didn't do anything about the Student Loan Rate. With a few exceptions Senators Elizabeth Warren and Bernie Sanders being the two loudest proponents, the Ultra- Reactionary Republican Party and the Pro-Business Democratic Party are enforcing the Neo-Liberal Economic Strategy in an attempt to grind the Middle Class out of existence and return the 99% to the Status of Wage Slavery; Cogs in the Gears of Industry and Massive Debt for a career in the Petty Bourgeoisie.
Of course, it shows the utter hyporcisy of the Free Marketers. The Stafford Loan rate isn't determined by "The Market" but by fiat from the Congress. So, it's just another way in which Capitalism is a rigged game, for the Banking Institutions get their federal loan rate set by the Federal Reserve. It's currently set at 0.75% for Big Predatory Banks.