Hi, author here. That was exactly my motivation for writing it. There's all sort of middleware and plugins out there for throttling from the server side, but I found nothing that would let me control my own outbound API calls to a an external service in Clojure. I also wanted support for burstiness, and that was even harder to find.
I bet you could come up with other uses for it though. Someone told me over email they're planning on using it in traffic simulation for a game, for instance.