So suppose if there's dust on your screen do you clean it everytime before closing the lid, that might be tedious! If not the particles can scratch while the lid is closed.I don't use anything between my display and keyboard - I don't get any marks or any issues. My computer is 2.5 years old at this stage as well.
The paper that is used during shipping is definitely not foam. It is in fact tissue paper.
http://www.pcmag.com/article2/0,2817,2411348,00.asp
I do have mine but as I said it's about to tear. I don't think it's tissue paper, look like some sort of tracing paper.Maybe for the 13", but it is definitely a thin foam sheet for the 15". I still have mine. Maybe check the box your mac came in if you still have it.