The basic structure of this argument is really straightforward: if student loans were dischargeable in bankruptcy, it would be irrational for a lot of student borrowers not to go into chapter 7 after school, when their earnings are so low that they qualify and their time horizon for major financial decisions is so far into the future that their current credit rating doesn't matter.
That's not entirely true.
For undergraduate students, no more than $57,500 can be loaned from the government at a fixed 4.45% APR. This is what you're talking about.
If you need more than $57k (which you would even at most state schools) you need to get a private loan. Private loans have variable APR based on your and your cosigners credit history. Sallie Mae offers loans with an APR between 5.74 and 11.85.
Also, not sure about the 4.45%. My federal are more than that.
Those are unlikely to be drastically decreased. What will drastically decrease is the amount of people, of any color, who can afford an art history degree. That is a good thing, especially for those who will be the first in their family who are going to college, and are therefore more likely to be swindled into one of those degrees in the first place.
As to why we require loans to be originated without regard to credit risk: if we took credit risk into account, disadvantaged groups would get student loans at drastically decreased rates. That, in turn, would undermine our bipartisan narrative that the way to overcome all the bad things America did to certain people is not to fix the resulting problems, but for everyone to get a college education.