How much should graduate students be allowed to borrow?

Last month WSJ did a study of the earnings of those who earned masters degrees at selective universities.  Those who studied business or engineering did extremely well, with annual earnings above student loan debt by a sizable margin.  

Labor market outcomes were less positive in other areas, especially degrees from elite universities in areas such as drama, education, film studies, and publishing.  Half of the graduates of Columbia's program in film studies earned less than $30k after two years in the job market.  Their median debt was $181k.  

Although this is an extreme case, borrowing for graduate programs has been growing and now represents half of student loan debt.  WP columnist Charles Lane pointed out that there are no limits on annual borrowing on Sallie Mae Grad Plus loans, whereas undergraduates cannot borrow more than $12.5k per year and $57.5k total.   It is quite possible that demand for graduate degrees would become more price sensitive if this issue were reexamined.  

Some have called for student loan relief.  For instance Sen. Warren of Massachusetts wants to forgive up to $50k of debt for all borrowers.  However a Brooking Institution study found that the bottom 60% of households would only receive 34% of the relief.  Why should MBAs earning over $100k get this form of relief?

I think there are two areas where borrowers could be better served.  First, one way to provide debt relief that makes economic sense as well is to reduce interest rates.  Currently the US government borrows money at close to a zero interest rate, but this year the Grad Plus interest rate is 6.25%.  Second, universities that participate in Grad Plus should be required to divulge to student borrowers data on labor market outcomes for graduates.  How many students would sign up for film studies at Columbia if they knew the likely prospects for graduates?