Old hat and new (innovation) are relative terms, and there are no black and white, but only shades of grey in using the concepts.
Beethoven wrote until 1827. Schoenberg wrote Pierrot Lunaire in 1912. So, in time, Schoenberg was closer to Beethoven than he is to us. Yet in the minds (ears) of many, he defined the beginning of "modern".
I was living in New York in the early, post LSD, 1960s when Cecil Taylor, Albert Ayler, Sonny Murrey, Archie Shepp,, and, for that matter, John Coltrane, Ornette Coleman, et al, were trying to fight their way out of perceived cliche's to the new.
That was almost 50 years ago. And they created in their struggles what became a language and idiom based on conscious iconoclasm. And it became, in a certain sense, a cliche' also. It was, and is, a brave struggle to try and create newness. But it will always become, at some point, old hat. The attitude of exploration seems more important than the actual idiom.
So, if Sonny Rollins could play St. Thomas, and have it be (great) jazz, not by idiom, but by attitude, why cannot current "tunes" be the bases, structural skeletons, of playing with the same sense of exploration and adventure as a 1960's Wayne Shorter tune (40 years old), or a 1940's Richard Rogers tune?
All that being said, I love playing "New York State of Mind", "Still Crazy After All These Years" "Just the Way you Are" eg because they are great tunes. I enjoy playing "Blackbird" because it is the one Beatles song that doesn't sound maudlin to me. I enjoy playing the Grateful Dead's "Ripple" and "Shakedown Street" because in an earlier incarnation as a sax player I recorded with the Dead, and therefore feel connected. Similarly "It's A Family Affair" and some other Sly and the Family Stone tunes. Time served, so they are "authentic" to me. Of course they are reharmonized enough to be interesting TO ME. But, because, in my neck of the woods, they are recognizable, audiences seem to enjoy them. I certainly do, or I wouldn't play them. No pandering here.
I wish that I could do "free improv" with the same players that I can make money with, playing music that unspecialized audiences seem to relate to, but it seems a special idiom. And I believe it to be an idiom, like bop, post bop et al.
Steven