They Wasted A Perfectly Good Plot / American Dad!

• Stan's rivalries with Duper and Chuck White.
• Linda's crush on Francine.
• Steve's relationships with Debbie and Akiko are completely forgotten past the episodes that focus on them.
• Jesus's proposition to Roger in "Rapture's Delight" (helping him rebuild civilization after the war) is never explored, as the viewer doesn't get to see what happened to the surviving humans after the Big Bad has been slain.
• "The Census of the Lambs" deals with Stan's exaggerated enthusiasm over the census, which gets deflected by his family and neighbors' apathy. The storyline opens a lot of room for discussion, but this is just the setup for the main plot, which is a parody of Silence of the Lambs. The villain for this plot also ends up being an Anti-Climax Boss whose defeat occurs off-screen, leading the entire episode to feel rushed.
• The revelation that almost every woman in Langley Falls is a member of the Ladybugs. They probably are still watching Francine so she doesn't spill their secret. Francine would continue living in fear.
• "White Rice" reveals that Stan had all of Francine's desires and thoughts that didn't entail her being an obedient housewife repressed for years on end. Any drama that could be had from Francine finding out Stan rewrote her entire life and personality is completely glossed over (Francine forgives Stan extremely quickly for what he turned her into) and the entire incident only serves as a lead-in to the actual main plot of her becoming a comedian before being completely forgotten in later episodes.
• Steve, Snot, Toshi, and Barry joining a boy band called Boyz 12 in "Can I Be Frank (With You)" goes completely unexplored in future episodes despite their one song being brilliantly put together and there is a lot of potential for other songs. "Russian Doll" brings the other band members back, but only to abruptly kill them off with the killer's (Abraham, one of the members) motivation going completely unexplained and ensuring that (unless it gets undone somehow) the subplot won't get explored anymore.
• The ending of the "Golden Turd" arc, in "300". After the titular turd's returned to the source —Roger— the world's transformed into a utopia. It would have been incredible to actually explore what this utopia was like. Perhaps with a montage of the Smith family (sans Roger) initially enjoying their new life, lasting a couple of days, where Smiths slowly get more and more bored with everything being so perfect all the time. But instead, the city (including the Smiths) just sings a Crowd Song, and literally, one scene later, the Smiths are suddenly bored with the good life. If the episode had just gone with the montage, it would have made the family's decision to end the utopian paradise seem more understandable and fair and less petty and self-serving.
  • There's also the fact that there was a whole secret society that knew about Roger and that he's the one who created the golden turd. It would've been great if they found out about the Smiths' plan to put him back together and set out to stop them, leading to an epic showdown where they would all battle the family, and remind them of all the bad things that Roger did over the years, possibly followed by a big speech about while he can be a jerk, he's still family. Unfortunately, as far as we know, the only ones who exist all end up killing each other over the titular turd, and the family managed to put him back together in an anti-climactic way.