I love it when other people say what I've been saying (although other people usually say it better). This is from Agoraphilia.

Here are some highlights:

Like it or not, some people are just not college material; they would be better served by vocational or on-the-job training (or by a better high school education than our public schools provide).

Moreover, the attempt to provide universal higher education has the pernicious effect of reducing the value of higher education. Radley Balko explains part of the story: as the supply of people with college degrees rises, the wages of people with college degrees will tend to fall (or, more accurately, not rise as quickly as they otherwise would, since other factors like technological progress tend to drive wages up). But the wage effect is not necessarily a bad thing -- competition is good, even (especially!) among people with desirable skills. My point, at which Radley also hints, is that the incentives created by policies designed to universalize higher education systematically drive down the quality of education.

Why? Three reasons. First, the policies in question typically provide education at far below its real cost. ...

Second, and relatedly, the existence of a large class of weak or unmotivated students changes the incentives of educators. ...

Third, the existence of (near) universal higher education has an undesirable effect on the quality of high school education. Students know, because they are told by their counselors, that a C average is sufficient to get them into a state university. ...

But read the whole thing, really.