The Family Guy pop culture references and whatnot are used for jokes. In South Park you're basically expected to laugh just because they are there. Kind of like how Friedberg and Seltzer movies are like "HA HA, HERE'S A CHARACTER FROM ANOTHER MOVIE!". South Park is like "HA HA HERE'S ROB REINER AND HE'S FAT AND EATING UNHEALTHILY BUT HE PREACHES AGAINST SMOKING HE'S SUCH A HYPOCRITE! HA HA HA HA!" Family Guy makes actual jokes, even if they're cutaways, so it's a lot better than a stupid show completely devoid in humor.
Haha, they broke the mold with you, BRTD.