It's a pretty common sentiment expressed that everyone, regardless of what career they're trying to do, should work in retail at least once in their life, just to understand what it's like to work with the public. There are way too many horror stories of people behaving horribly to retail workers, treating them as if they were slaves or public servants instead of people with lives and emotions of their own. So one can hope that more people experiencing a retail job can grant those people more empathy and kindness.
Some people don't consider retail work to be challenging, but those who actually work in retail and have to deal with angry customers on top of their other responsibilities will tell you otherwise. Working in retail gives you the opportunity to learn how to work and solve problems with other people, and can give you a good work ethic. It's easy to wake up and go to work once, but not as easy to have the motivation to keep doing it day after day.
Working in retail also provides the challenge of people able to work under pressure, a skill which is valuable to have in the work force. Not every manager is the same, just as not every customer is the same. Thus, working in retail will grant you patient as well as the skill of having a positive attitude (something which is often required). Multitasking is also something you learn how to do in retail, as you will often be dealing with several different problems at one time.
Those who look down on retail work as being "lesser" would most likely change their tune if they had to deal with the long hours, challenging customers, hustle of the job, and the problem solving. In the end, I agree with the idea that everyone should work in retail or food service at least once in their lifetime.