The need to get a job is so great these days that job seekers are willing to do anything. They would even apply for jobs for which they are overqualified.
Employers are reluctant to hire overqualified candidates. There is too much of a risk that such employees would become unhappy doing work that is below their skills. This would make it more likely that they wouldn't stay at the organization long. It's not in the best interest of an organization to hire an employee that will leave after a short time. Overqualified candidates can also be threatening to interviewers, because there is the distinct possibility that they could take their job one day.
All this doesn't mean there aren't good reasons to apply for a job that is way below your talents. You will rarely be told during a job interview that you are overqualified, but you can still explain your reasons for applying. For example, there could be a situation that came up in your family that requires you to take a position that is far less stressful. This will ensure the interviewer that their job is not in danger, and that you have a very good reason for wanting a low level job.
Applying for a job out of desperation is not a good reason, as tempting as it is. Before settling for a job that you won't be happy with, search harder for work that fits your skill level. It's best for you and the employer.