Yes, jumping does have advantages on the serve in terms of the angles you get into the court. I'm not necessarily against it except that it can make the serve motion inconsistent and ends up being a net negative. In terms of ball speed, however, its contribution is small. Think of how long it would take you to hop to the other side of the court with that motion.
No question that Brian Battistone's jump helps his serve. It is really impressive to see in person.