When I heard it, I heaved a sigh of relief. It really is ok to talk to people about something they've heard before.
But similar to this, I think there's a different fault that we often commit. That is, every time you reference a familiar story, you just say, "You all know the story of....", then you suck the point out of it. It's like the old poem about Little Jack Horner:
Little Jack HornerWhen we go ahead and pull out the plumb we are wanting, we are robbing our audience of the experience of reliving the story.
Sat in the corner,
Eating a Christmas pie;
He put in his thumb,
And pulled out a plum,
And said 'What a good boy am I!'
I think another flaw in this approach is the assumption that all our listeners are biblically literate. I am regularly shocked at just how little most people--even Christians--know about the Bible. I think some of the most powerful stories in the Bible, such as the Creation narrative and Noah's experience with the flood, are often overlooked as kid stories. We think, "I learned about that when I was little," and we never give it a serious hearing.
I think good preaching is textually-centered preaching. We need to chew on each verse as if it were a high dollar steak from Ruth's Chris.
If we really help people to re-live and re-explore passages, whether they are familiar or not, our sermons will become more engaging. I would encourage preachers to slow down. Rather than referencing 3 or 4 parables as quick illustrations of a point, why not really live in one of the parables for a sermon? Even if they've heard it before, help them to see it through new eyes. As our situation in life changes, our perspective changes. This is why we can read the Bible through year after year and still hear it in ways that we've never experienced before.
So for now, slow it down. Spend time in the text and allow it to be your authority, whether it is familiar or not.