The ol' puritanical work ethic. No, you need to make the best business choice. If a corporation defaults, no one cares. But your degree is worthless or provides you no benefit? You never get away from it.
When you can walk away, walk away. Its okay for the Fed to QE till the cows come home to prop up asset bubbles, but not okay for the US DOE to forgive loans on educations that have little value? Please.
I guess it just comes down to the type of slavery you want for the next generation. At least you have the option of not buying a home or equities in inflated markets, but garnishing your wages or your tax returns forever? We should be shocked about those who don't emigrate to countries that treat them better. I'm very surprised first world countries with declining populations haven't made an active advertising/outreach effort to appeal to young US graduates with large amounts of debt.