Besides the psychic boost, telling traditional folktales has helped develop my picture book writing. This is largely because of what those tales leave out. Setting is seldom more than mentioned, while characterization is limited to broad strokes. Internal musings are nearly forbidden. Flashbacks don't happen.
Abstractions are taboo.
This, of course, is the aim of the picture book writer. And I can't help but get a feel for it when I learn and tell folktales. Storytelling helps my writing even more directly by letting me test my own stories in performance. We authors are often warned that the kids we know don't make good judges. But, let me tell you, a roomful of young strangers makes a very good judge.