Copyright is both a safety measure and a restriction. It prevents work from being stolen or used without consent. But it also prevents fans from drawing too much inspiration from a work. In the various media communities, fan fiction plays a big role in maintaining and strengthening a community. However, copyright prevents these fan works from being easily distributed without gaining legal attention.
Once again, as a fan of anime and manga, I have seen things function differently in Japan. It not only seems like the copyright law is more loose, but fan works are even encouraged. Many places are known to hold conventions for the distribution and selling of fan made parody works. And these don’t just include books, but games, and even animation. Despite working on preexisting and copyrighted works, artists and writers are discovered and make themselves known.