This is inevitable in The Simpsons, where the first five to ten minutes set up things that later turn out to be unrelated to the main plot:
- The episode "I Don't Wanna Know Why the Caged Bird Sings" starts with Marge yelling at Homer for not going to Lisa's award ceremony, Homer decides to prove her wrong and wants to make sure that he is in the auditorium before anyone else. This seems to be the main plot of the episode, but then it is forgotten and the main plot is about Marge and a bank robber and has nothing to do with Homer getting to Lisa's ceremony.
- "Homer The Whopper" could have been a funny episode about the making of a superhero movie in the vein of "Radioactive Man", but instead focuses on the overused plot of Homer sticking to another diet (and failing it), with all the movie stuff happening in the b-plot.
- The episode where Maude dies. It could have been a Tear Jerker Heartwarming Moments episode (and it was a little bit, especially when Flanders briefly denounced his faith in God and met Rachel Jordan after going to church), but more than half of it was Homer setting up Ned with horrible new girlfriends (even though Homer wasn't being a jerkass about it; he was genuinely trying to help Ned out).
- Some found the Fake-Out Opening about Bart digging and the Chinese spying on him more interesting than the actual plot in "Homer the Moe" and were disappointed it turned out to be a "Shaggy Dog" Story that wasn't followed up on.
- Mona Simpson's death, for similar reasons as Maude's: Her death comes out of nowhere and lacks gravity, especially since the funeral was off-screen, and it is quickly forgotten as the story progresses-the rest of the episode focuses on the Simpsons sabotaging Mr. Burns' rocket launch (a plot that could have easily been done without her death). Though the sabotage was Mona's last wish.
- Many viewers felt that the first act plot of Season 19's "Husbands and Knives", starring Jack Black as the owner of the new comic book store across the street from The Android's Dungeon, was superior to the rest of the episode, which focused on Marge starting a franchise of women's gyms and Homer getting plastic surgery in fear that his newly-rich wife will run off with another man.
- The episode "Simpsorama" didn't make a single comment about the different skin tones of the cast. While the Family Guy crossover already did this, it still feels strange that nobody seemed to notice, considering that Fry lived in that time period and nobody was portrayed as yellow.
- Fry didn't get to do much in that episode. We even didn't get to see the events unfold when Professor Farnsworth asked him to team up with Homer in a nuclear powered experiment.
- In "To Courier with Love", there is no mention of Bart's time living with Ceasar and Ugolin in France, despite them all being in the same room. They act like they've never met despite the fact they treated Bart like dirt and he got them arrested.
- Any of Marge's one time jobs could have given her some needed Character Development beyond the nagging housewife and mother role she plays, but especially her stint as a police officer. Marge was awesome as a beat cop, and, as shown in the episode where it happened, it gave her an excuse to interact with the rest of the town and contrast all its seedier elements.
- Edna Krabappel is a walking example of this:
- Early in the series run we find out that she's a divorced woman, whose husband left her for a younger woman that also happened to be their marriage counselor (for added "fuck you" level of bitterness). Yet we NEVER meet Edna's ex or his new wife. NEVER. The writers contemplated introducing Mr. Krabappel in the season two episode "War of the Simpsons", with the idea of having him be a Dean Martin lookalike. But they decided instead to include a rip-off of Elizabeth Taylor and Richard Burton from "Who's Afraid of Virginia Wolf?" instead.
- Her relationship with Principal Skinner was another wasted plotline. It gave both characters added depth and pathos, fleshing them out into fully developed characters and even led to an evolution of their relationship with Bart, who supported their coupling. Sadly, one of the very first things Al Jean did when he came back to the show, was kill the relationship dead. Principal Skinner never recovered as a character, while any chances of Edna and Seymour reuniting was crushed by the writers pushing Edna/Ned onto fans out of the blue.
- Finally her death; rather than giving the character a proper send-off, she was written out in the worst possible way: a one-off dream sequence that has no connection to the main story of the episode it came from with Ned simply saying "he was going to miss her" while Nelson does a half-hearted "ha-ha!" before agreeing with Ned about missing his teacher. Since then, the show barely makes any references to her, in terms of her becoming practically an unperson and writers shoving all sorts of substitute teachers into the mix whenever they have to do a school centric Bart episode before finally settling with new character Rayshelle Peyton—almost a decade after her death.
- On the topic, while fans like Mrs. Peyton well enough, her debut episode never clarifies why Ned is no longer teaching after taking the job four seasons ago. So much for carrying on his second wife's legacy...
- Season 34's "The Many Saints of Springfield" finally clarifies that—as in his brief stint as school principal in "Sweet Seymour Skinner's Baadasssss Song"—he was fired by Superintendent Chalmers for exposing his students to his Christian faith while on the job. Aborting the arc killed a unique opportunity to explore the existing dynamic between Ned and Bart that was emphasized in The Movie (although Ned's presence at the school led to one episode, "Better Off Ned," dealing with their relationship, it largely covered ground already covered by said movie and didn't address their teacher/student relationship at all).
- Everything we can say about Ms. Krabappel's death following that of Marcia Wallace can also be said about the show's removal of Phil Hartman's characters Lionel Hutz and Troy McClure. Like Edna, Lionel and Troy were immensely beloved and irreplaceable characters in the eyes of both the fans and the producers, but when Phil Hartman was murdered, the series did absolutely nothing to close the books on these characters, which could have also been a great way for the show to pay its respects to Phil Hartman. While the show did wrestle with how to draw the curtains on Krabappel for a bit through episodes like "Left Behind" and "Diary Queen" and created a massive Tear Jerker of a Chalkboard Gag in "Four Regrettings and a Funeral" to pay tribute to Marcia Wallace, Hutz and McClure were pretty much un-personed from the show while Phil Hartman only received a small dedication In Memoriam during the credits of "Bart the Mother" (his final appearance in the show). The fact that Hutz and McClure still make cameos in the series in crowd scenes only further demonstrates the writers' apparent indecisiveness to give either character (and their actor's role on the show) a meaningful farewell, with the series itself pretty much acting like nothing has changed following their disappearance.
- The show's response to "The Problem With Apu" could have been a tactful way for the show as any Long Runner would to reconcile the social changes over the years that make classic elements/characters age badly especially as Hari Kondabolu made an articulate, respectful case as a long-term fan who, along with other South Asians, had to deal with being compared to Apu growing up. Instead, not only does the show shrug it off as "political incorrectness" like the argument was just brushing off another Media Watchdog, it chose to do so through Lisa, the one character who'd be siding with the documentary regardless of her friendship with Apu.
- "Bart vs Itchy and Scratchy" had an interesting premise going on, with Bart unexpectedly enjoying a girl's show (one that was also an all-female reboot of his favorite cartoon)in a moment that Lisa witnessed. This could have lead to a story about them bonding over the reboot, but instead Lisa skips straight to humiliating him over the internet. Or the plot could have involved him mingling with some of the girls who are a severely underused group of characters in their own right, again focusing on bonding over the new I&S. Instead none of the female cast even have lines outside of the main family and Luanne, the plot is taken over by three guest voiced characters who lack distinctive personalities, aren't named in the episode, lack any redeeming or likable qualities whatsoever and will likely never appear again so there's no significance to them.
- The female version of Itchy & Scratchy could have been used to Satire that media companies will make "female" reboots of established properties for good PR rather than put the effort of making original properties with a female cast.
- In "The Girl Who Slept Too Little", Lisa is afraid and starts to sleep in Homer and Marge's room. She hears them complaining about seeing Apu and Dr. Hibbert at a party. Lisa is surprised that adults say bad things about other people behind their backs, and questions if it's morally right. Marge distracts her, and this idea isn't brought up again.
- Homer and Marge competing on a game show in "Heartbreak Hotel" could have made for an interesting episode by itself, but they're eliminated during the first challenge and the show is essentially forgotten in favor of yet another "marriage crisis" plot.
- "Mathlete's Feat": The idea of Springfield Elementary using advanced, modern technology following the sponsorship is interesting and something that we've never seen before. However, after the EMP, it goes back to more jokes about the school being low-budget, which has been done numerous times before on the show ("Dog of Death", "Lisa Gets an A", "It's a Mad Marge", "The PTA Disbands", among others).
- "The Winter of His Content" has a brief mention of Homer's grandfather being alive. Lisa is shocked at this revelation. However, we learn nothing more about him after this, and he is not brought up for the rest of the episode.
- "Clown v. the Board of Education" caught criticism for its abrupt third-act twist of Fat Tony getting involved with Krusty's school, further rehashing the plot of "Homie the Clown" when the episode actually did have a few more interesting plots it was setting up (Krusty's clown school competing against real schools, or Lisa trying to prove that she can be fun like Bart) that are all dropped.
