I always dislike when the "innovation" buzzword is applied to any form of art and/or is somehow used as a value descriptor of art. How can art "innovate" anything, really? Applying the innovative tag to art attempts to define it in terms of technological progress where innovation means something that does the job of the thing it replaced cheaper and more efficiently (i.e. horse carriages to cars). Artistic value is obviously subjective, and the primary elements of artistic value are a person's emotional and intellectual responses. A horse carriage will never get you to a destination as quickly as a car all things being equal, therefore the horse carriage is obviously "antiquated" as a mode of transport, but a 1920s Blues song can produce the same level of emotional and intellectual engagement as anything modern. On a related note, this is why calling a piece of art "dated" or "aged" is also nonsensical.
Someone might try to describe innovation in art as a change to a preceding artistic trend (i.e. the Rockabilly of Elvis, Buddy Holly to the British Invasion to Psychedelic), but the ensuing development doesn't make the preceding trend "obsolete" in the technological sense. Buddy Holly is Buddy Holly, and his music produces a different experience than the music of the Velvet Underground. The two artists don't "compete with each other" for technological viability. Change doesn't equate to superiority in this case. It's just that. Change.
Saying "everything's been done in a genre" falls into the trap of, again, placing art within that obsolescence/innovative technological paradigm. "Well, we've exhausted all the possibilities of the internal combustion engine. Nowhere to go." Art is first and foremost a "formalized expression of experience." As long as there exists people with "something to say," art can't be exhausted of its possibilities (Bob Dylan and Leonard Cohen sound superficially alike, but are actually nothing alike). This is even true mathematically, as there are a limitless number of ways to construct a melody. Then add on top of that the limitless amount of tonal, rhythmic, and temporal variations.