I've learned that Fair Use is what protects others' creations from being stolen and used elsewhere under someone else's name. This is important because it gives credit where credit is due, something not easily available with internet pirates. (Take, for example, the Meme. Though many pictures like that are used in good fun and people understand what is being done with their image.) Searching for images under CC, while limiting the selection, allows for free images, safe to use in a variety of situations.

Image from http://www.public-domain-image.com/animals/bear/slides/black-bears.jpg and posted under Fair Use Agreement.