I can't tell how much of this is serious, but... seriously? Why do you assume that new material can only be "new" in some incredibly superficial sense?
The old material was once new, and the new material gets old in turn. Literature reflect changes in society, politics, culture and language. This is not a measure of freshness, it is a measure of how the present is reflected back into writing. Combine this with an unwillingness to accept the connection to what has gone before, and "new" ideas ends up disjointed and temporal. Superficial in the sense that many contemporary ideas cannot stand the test of time, unless they acknowledge that everything new must eventually grow old, and as such you must be able to relate it to that which has come before, before it can have a place in the future yet-to-be. If you can bridge the old and the new, you have come up with something that is not superficial. You have made something ageless. As for the rest, it will be forgotten, but for a few that likes to dig up things destined to obscurity. In that sense new material ends up superficial, from the perspective of time itself. Not necessarily as a failure in a contemporary timeframe.
That, and for all the changes taking part around us, the basic elements of the mind lag behind in a physiological sense, so that fundamental desires for story elements and plot devices follow deep patterns. New stories take the place of old ones, but serve the same purpose. There might be extra layers present in order to device new twists and turns, but that does not change the basic content within. And without that basic content, the storytelling more than often ends up as an empty shell, drowned in the effort to tell the story in "new" ways.
All this talk is thirsty work, you know. Will take some time to take out the dryness of that mouthful!
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