Outside of absolute necessity, there are other reasons people might want to work below their current capacity. The archtypical "day job." I've been working on a personal project which I hope to evolve into a business. I took some time off to do this in March. My finances are starting to run low and I've been looking for an easy job which will pay my rent and maybe have health insurance, and have had many of the problems described in the article. I was offered a job as a CTO of someone else's startup, but the nearby college won't hire me as a PHP drone.
I quit my job last October to try some writing (which unfortunately isn't going well) and some studying. I, too, am running short of funds, but got hired for a low level position at the local Walmart, which more than meets my bills, and gives me plenty of time to think about what I want.
Here in New York we're having a miserable time hiring new grads for IT, worse than last year. We recently signed on with a headhunter, just for the sake of trying something else.