No offense, but modern family guy ranges from okay at best, to a sheer atrocity at worst. It's cringey, unfunny, repetitive ( it's been doing the same thing with absolutely no sort of variety for years now ) and extremely distasteful. While I agree that Seth should be allowed to make the show how he wants to make it, an easy counter argument would be the perverted, skewed and downright terrible morals that the show attempts to teach to it's 14 year old audience. A bad show can be taken at face value, and simply just stand as just that - a bad show. But a show that actually sustains itself on giving potentially harmful and downright idiotic messages to it's fan base, with absolutely zero regard for any sort of negative influence or impression that it may leave on it's audience is more than just " a bad show ", it's and atrocious show. And with some of the sheer B.S that Family Guy has pulled in it's more recent years ( Not all Dogs go to Heaven, Screams in Silence, Herpe the Love Sore, Brian's a Bad Father, Seahorse Seashell Party, Fresh Heir and more, which all stand as some of the worst episodes of any cartoon ever made ) the hatred towards it cannot be just attributed as " seasonal rot " or " becoming stale ".
Many people which Family Guy loves to parody, treat their problems like a joke and give some of the most insultingly simple and/or contrived methods of dealing with it, have to put up with this show completely and commonly flanderizing the true nature of their respective situations, and that alone is enough for it to be considered one of the worst cartoons ever made. The excuse that it's just harmless and dumb fun can no longer be used when that " fun " is no longer harmless anymore. You have influence Family Guy, you can't just keep acting like you don't.
Also there is a world of difference between a show " handling itself differently " and a show being in very poor taste. Rick and Morty is a really well-done and entertaining show that also happens to feature adult orientated jokes as well as teaching a subtle, competent and mature moral. Family Guy is just a bloated collection of extremely unfunny and distasteful jokes, with virtually no sort of substance outside of being distasteful. And when it DOES try to teach messages, oh GOD does it screw them up in the worst way possible.