This is what I get for coming up with a one-liner response rather than my usual extended babble.
What I meant by my short-form comment is that, in essence, what you are valuing is the ability of the writer to do something new, something different, something beyond the mere four corners of the existing canon. As you say, adding a piece of themselves: to take the source material and add something that is entirely new--hence, original. Merely copying the original will not do it for you (I can certainly understand that; the problem with such copies is that that since they can never recapture the original mindset of the author they will never be as good); there has to be something else, some additional factor that can add to or even surpass the original material. It's not rehashing tired old concepts, but bringing something new to the table--something that takes genuine creativity.