Um, hate to be the odd one out, here, but I disagree. Not because I can't see why Hagrid/Snape/Draco/Molly/whoever wouldn't be dislikable if they were real people, but, you know, they're not real people. Every character serves a function in a well-written piece of fiction. Hagrid's stupidity, Snape's cutting sarcasm, Molly's smothering, Draco's futile insults all have their purpose. I can like a character that's well drawn and enjoy seeing them do their thing whether or not I would actually like that kind of person in real life. I find Voldemort disappointing because as a bad guy, he's a lot less scary to me than the sweetly righteous Umbridge, and bureaucracy scares me more then Death Eaters do. But I don't hate him; I just don't think he serves his function in the story very well.