With student debt its different, if you went to undergrad at MIT then did an MBA at Standford - you are probably looking at north of $100k in debt. If one year after college you defaulted and it was discharged, you would still retain the 'asset' (your education). You could go out the next day and get a nice job at google and continue to earn income from your asset. The bank has no recourse to prevent you from continuing to use the asset they loaned you money for. This is one of the main reasons that you can't discharge student loan debt. No one is going to come take your degree away from you if you don't pay.
I realize the loan in these cases is not directly from the university.
I went to Harvard, its just I lost the degree in bankruptcy, so they claim I didn't go. Just call my references (which are actually burner phones held by my brothers)
Interestingly higher ed already requires all bills to be paid to graduate... they don't care if you default on your credit card the week after graduation, but you aren't getting the diploma until the library fees and tuition are paid off by "someone, somehow". Once its the loan servicers problem, they don't care and you get your diploma. I vaguely recall having to get a slip from some different offices proving I owe no money to the school, in order to graduate, and threats they wouldn't provide transcripts to students in collections, etc.
I'm not saying the judgement / assumptions would be correct, but it's quite possible some employers would act this way all the same.
Therefore it's a big incentive to pay your money back.
Plus, if the potential employer checks your credit history and sees you defaulted on your student loan, they may make assumptions about your behavior or character, having a definite impact on their hiring decision.
Call it professional courtesy.
Regardless of the students' situation, that money going to get paid, come hell or high water.
FWIW, I have no student loan debt so I'm relatively neutral on this.