If there was one character they should have killed off, it's Meg. The "Let's all be mean to Meg" jokes haven't been funny since the show's, like, ...ever. But that would be obvious and they wanted to "shake things up." I think they want to sabotage the show so the thing can finally end.
The one thing I actually liked was when the writers became aware of that, and played with those aspects and slapped them back in his face. His breakdown on the Bill Maher show and his confession of wanting to commit suicide were pretty character building sequences. Then of course, Quagmire's "Reason you suck speech" and Stewie comforting him later. Again, this happened much later than it should have.Another reason I can't be too sad about Brian's death, to get back on topic, is that not only was he really unlikable (he almost seemed like the snotty, pseudo-intellectual moron who thought he was just the smartest guy around; I'm sure we all knew this guy in some form as teenagers), but that early on in this characterization, the writers made it seem like he was this paragon of intellectualism, depth, and social awareness, when he really wasn't much better a character than anyone else on the show, in that regard.