"When Seth was in the writer’s room, he was the best writer there," explains Sulkin in the interview. "He made the show better just by being there. He was certainly stretched a little thin by all the projects he was working on, and while we have a lot of other talented writers, it was bound to affect the quality of the show."
At the same time, the interview isn't a series of excuses, and it's worth reading in its entirety. Sulkin appears convinced that the show could recapture some of its old magic by returning to more grounded plots, exploring new topics, and bringing in new writers. He's actively looking at fixes. For the show's loyal audience of Stewie enthusiasts, this might be a sign of hope, and if you gave up on the show at some point in the last 10 years, maybe tune in. If you thought the show always sucked -- well, it's probably not going to win you over now.