I once worked at a company that did something like that. It was optional, but once a year you could spend 3 days working in first-line customer service. A CS rep oversaw your responses, but you got an ordinary account in the customer service system and dealt with real customers.

The first two days you spent replying to customers, and the third day you spent prototyping or writing up some way that you thought common complaints could be addressed by making changes to the product.

It was a nearly unmitigated boon to the company. Sure, the company saw it as paying for a few extra vacation days. But the program stuck around because it generated a lot of good ideas, and the direct communication between CS and product development teams was valuable.