The best purpose of college is to make you a reasonable citizen in a democracy. Most Americans voting in elections can't even name the Vice President, let alone articulate what plenary powers are, what the 4th and 5th amendments say (or seriously any amendment), name more than 3 executive branch departments (Defense, State and... uh...), point out where Iraq is on a map, etc. It's really no surprise we get the elected officials we get.
Sure, professional training is important and I think our education system is not particularly efficient about it. But education is more than just "here's how you work for the man". It's supposed to make you a well-rounded, well-educated citizen so you can participate effectively in a democratic government.
Which is why things like public education, state colleges and universities, a separation of religion and education, and state subsidized college tuition are so important, and why religious schools, charter schools, and for-profit colleges/universities are so antithetical to democracy: their agenda is entirely separate from "be a well-educated democratic citizen".