I have read several newspapers and reports that the united states is actually over-saturated with college degrees. This obviously makes the value of them less and levels the playing field. Essentially meaning that you need a college degree to even be considered for many of the jobs on the market today.
When the population of people with degrees increases, those who have the degrees are less special in the eyes of the employer. In the past people with degrees were more uncommon and stood out against the sea of other applicants without degrees, thus making them an easier decision. Now people with degrees are competing to be under-employed right out of college so that they do not drown in their student loans. Overall it does help to get a degree in today's job field, but there are plenty of other people out there who look just as good as you.
While it is historically unprecedented and a sign that human beings are capable of at least trying egalitarianism, the commonness of the bachelor's degree has made it no longer the reasonable guarantee of a job that is commensurate with one's education or a good salary with benefits that it once was. Except for low wage jobs where being too educated is viewed as a risk that an employee will run off at the first chance, it is harder and harder to get a job without an college education. It is wonderful that people who want to be educated at a university can, but others are just not academic and the insistence on a 4 year degree hurts them. They're intelligent and capable of learning, but they don't do school. There's also people who aren't poor enough to get grants but still too poor to actually afford college without loans that are going to make the next 10 or so years really hard. The master's degree is becoming the new distinguishing education and where it used to be the masters, the doctorate. The time and money investments that these require still make them prohibitive to many people. There's definitely a growing amount of highly educated but still under qualified workers out there.
I do not believe degrees are less valuable because more people are getting them. I think degrees are less valuable because the American workforce and employers are obsessed with low-wage work and low-wage ideas. They make more profit by underpaying people. Degrees are still a great resource for people, especially when they live in an urban environment where there are more jobs available.