Note that Kissin is not a jazz pianist. Rachmaninov is not a jazz composer. But check out the first piano arpeggio in this movement of the piece. I once asked my room mate, a classical pianist, to try to improvise for me. I noticed something very intriguing. He already sounded better than a lot of jazz pianists I know just because he had such a vast classical vocabulary. He took the riffs and arpegios, etc. that he knew from classical music and applied them over chords. What jazz musicians often don’t realize is that they can do this too! There’s an infinite world out there of beautiful material that can be used. This arpegio is a great example of such an instance. It is very different from the typical jazz arpegio which tends to just arpegiate a chord, but Rachmaninov adds in extra notes for color and effect. Why not do the same jazzers?