"Of course"

Why do radio news announcers sprinkle "of course" into every third sentence? Examples:

"Kerry, of course, leads New Hampshire primary polls by a comfortable margin..."

"The Lord of the Rings has of course been nominated for several Golden Globe awards..."

The dictionary definition is "as might be expected," but the colloquial use is more like "it's universally known that." Problem is, news announcers apply this to things that are not universally known. In fact, if the average listener knew both the facts in the examples above, nobody would need to listen to the news.