Cautious response to PhD loans proposal

As far as I can see there is no shortage of studentships for Home students in the natural and engineering sciences - we easily fund as many PhD students as we need. Others can maybe comment better on the social sciences and the humanities, perhaps there is a case for a few more studentships, but I suspect that the economy is not crying out for too many more English PhDs. So who benefits from making subsidised loans available? Most likely not the student, when they have spent three or four years amassing debt when they could have been working towards a rewarding career.