Economic- college prices are astronomical. Absolutely massive. So massive most college students couldn't afford the rates on their own. So how in the hell can colleges charge so much? Federal student loans. The colleges build in loans when considering student budget, making their rates much much higher than they would be otherwise. Since 1965 when the loans were first implemented, rates have grown exponentially. Bottom line- Federal student loans write colleges a blank check, so obviously take advantage of it.
Social- Fed. loans don't distinguish between choices of study and their lucrativeness. This is a foolish denial of reality, leading to the debt we see today. This is because it makes the false assumption that all career paths lead to equal financial footing, and equal ability to pay off one's loans. The tendency to ignore this breeds obliviousness in college student, until it's too late. It also has devalues what college degrees are actually worth is in the job market.
Moral/legal- The Constitution mentions no power granted to the federal government in relation to education, so the federal government has no authority to fund it or establish it. That is a State matter. It's called federalism folks. Plus, it gives credence to the argument that federal funding is justified because education is a right. This is false. It's akin to suggesting that the government is responsible for providing a taxpayer-funded firearm to every adult in the nation. Both propositions are ludicrous.
I have written an essay that is much more in-depth on this topic, countering potential rebuttals or rebukes, linked below.