Having looked at your slides, I would say we pretty much agree. I think employers have little control over the content of college education and, as you say, use quality of college because it works better than IQ tests and the like — as you say.
Perhaps we also agree that just as British aristocrats have a lot less power now than they did 200 years ago — the message of Downton Abbey — so are American college professors slowly losing power. MOOCs are one example, blogs are another. Parents and professors are quite happy with the current system, students and employers are not, and they are gaining power. That is my theory, anyway.
I think a signaling explanation does a very good job of explaining why sense of humor matters so much, especially in mate choice. Sense of humor = Nature’s IQ test. Sense of humor signals problem solving ability, which really matters but is hard to measure directly. I used to think that we have two basic tasks in life, manipulating things and manipulating other people (long ago nobody was depressed, etc.) and they were really different.