The Great Whistle Mystery

Why, when a half-time or full-time whistle is long overdue, and the ball goes out for a goal-kick and everybody KNOWS that the whistle to terminate this particular portion of "entertainment" will follow next and it's freezing cold and everyone just wants to have a break and get their mitts round a hot toddy, does the referee, instead of blowing his whistle straight away, ALWAYS wait for the goalkeeper to retrieve the ball, place it in the six-yard box and boot it downfield, a process which can take up to half a freezing minute, before blowing said whistle?