It's all well and good to have anti-heroes as main characters, but there are some protagonists that just piss me off. I really like Tales of the Abyss but the main character is such a whiny, childish, jackass that it makes the beginning of the game very difficult to sit through. The main characters from the Devil May Cry games are also pretty insufferably annoying. The games may still be good but the protagonists really detract from the overall experience for me. Overall I don't think it's absolutely necessary for them to be likeable, but it definitely helps.