Regarding the original characters thing, I do think it's a matter of expectation to some extent. I tend to go to fanfic because I fell in love with the characters and wanted more of them, and to resent original characters for overshadowing the canon characters. But some people enjoy original characters; it's how they relate to the canon, by putting original characters in it. I've written them myself but they were never my reason for being in fandom, because I had original fic for that - but I can see how, if someone didn't have that original-fic place to go to, it could be a necessity (I would shrivel up and die if I didn't create original characters *g*). So, yeah. It's a prejudice (and one that I've been guilty of), but like you said, fanfic can be a great place to develop an original character with a familiar backdrop to place them in.