First, here is the definition I found for derivative art in the context of art, via About.com:
Art that is based on the work of another artist or school of art, or uses all or part of another artist's work in it.
This term has me on the fence, but I lean toward the idea that an artist makes a work her/his own.
Sure, I am concerned about having my work copied or passed off as someone else’s. I’ve known artists who have been taken advantage by others. One told me that someone photographed her work at a show and later sold prints to a hotel. Another arranged with someone for prints of her work to be made and sold. Then she received only one check before finding out that the person had skipped town. At any rate I don’t fool with prints. I concentrate on making originals. If someone takes advantage, I’m taking the risk since I’m not getting any younger. Having my art seen is more primary, just now.
In the last few years I have noted the creativity of folks on the Internet who recycle images and ideas with their own stamp. If anything their enthusiasm and playfulness have inspired own art creation. It is still popular to rework something old, but my sites are set on making something mine.