The coaches do not want the Kickers to sail the ball to the back of the end zone during scrimmage, they want them to kick it short, so that the return guys actually get the chance to field and 'return' the ball. During the season you are going to see plenty of kickoffs 5/6 yards deep in the end zone with the occasional ball being kicked out of the back of the end zone. It is not as bad as you think it is.