Eric Cantor is a *******. This is typical government accounting...move money forward so it looks like you "make money" right now. The interest gets paid either way, its just that if they start making people pay it in school the money starts flowing in 4 years earlier. This only "saves money" if you have no idea what you're talking about.
Not to mention if they did that there would be no such thing as student loans anymore. They'd just be...loans. I can see private companies being happy to step in with a pitch that basically says "Screw the government...we'll give you a loan that you can defer during school" because they know they get paid at the end of the day either way.