I know it's a little late, and I know it's off topic: but no, you can't use the word retarded like that. I am really pretty offended by the word used in that context, as I work with people who are, in fact, retarded.
And maybee, you're wrong. I agree that Wakka isn't a well-written character, but Pike is right. You don't always LIKE the characters you're reading about, but that doesn't mean that they aren't good characters. If they're bringing out an emotional response in you because of how they are as a character, they author has done something right. Try reading Valley of the Dolls, Revolutionary Road, or Lolita. They're all books which deal with unlikeable people with severe issues, but have deep, interesting, and thought-provoking characters that make you uncomfortable and have to evaluate your thoughts about them, as well as the possible sympathies that spring up, especially when you know they're bad "people."