I don't think 'retained knowledge' is the best metric for deciding if a liberal arts education is worth it. A degree, particularly a liberal arts degree, seems (in my admittedly limited experience) to be geared towards honing critical thought, and the ability to express ideas well. I think this is important. And even though a lot of students may take it to the extreme, I think partying/socializing in college may be important too.

Ultimately, I think the issue is with insane tuition prices, not with people who want a liberal arts degree.