Right, Sam. Seth MacFarlane is the writer and artist for these shows, as well as The Cleveland Show (which is just awful.) Fox tends to stick with things that work for them. MacFarlane tends to push and see how much he can get away with. These shows get tired after a while, but it's not a conspiracy.
When my little one was really little, maybe 5 or 6 (yeah, I'm a bad mom, I let her stay up and watch Family Guy a few times) She saw American Dad and said, "Family Guy and American Dad are the same show... except American Dad isn't as fat." Out of the mouths of babes.