History Main / NecessaryWeasel

* {{Fanservice}}: Such contexts as bathing, swimming, or exercising are a very good reason to show people off wearing little or nothing, and spiritual nudity is often considered another legitimate form especially in Japan. There is also debate on what types of flesh exposure through clothing in general (usually female) come naturally to a given artist or are even justified, or are designed purely to titillate, although plenty of instances ''are'' clearly the latter.

* {{Fanservice}}: Such contexts as bathing, swimming, or exercising are a very good reason to show people off wearing little or nothing, and spiritual nudity is often considered another legitimate form especially in Japan. There is also debate on what types of flesh exposure through clothing in general (usually female) come naturally to a given artist or are designed purely to titillate.

As a logical extension of Administrivia/TropesAreNotBad, many tropes that might otherwise come across as gratuitous, offensive or just plain wrong in most genres are considered not just accepted in certain genres, but are practically a part of the genre. Complaining about the simple use of the tropes (as opposed to particularly offensive variations) in said genres is rather short-sighted and pointless, since, well, it's in almost ''every'' other work in the genre.

** TransportersAndTeleporters were cooked up entirely to keep from having a DropShip sequence from eating [[Series/StarTrekTheOriginalSeries a certain show's]] entire budget, and were [[MisappliedPhlebotinum consequently poorly-implemented.]] The device as described completely breaks both conventional physics and quantum mechanics as we currently understand them over its knee, but there's no story (or, at least, more [[BottleEpisode cheapo episodes]]) if the shuttle animations budget guzzles up the action sequences. Having the actors disappear and re-appear elsewhere in a cloud of sparkles is much cheaper.

* FasterThanLightTravel: Usually present in space-based ScienceFiction and virtually all SpaceOpera. Without it, you can't really go anywhere other than the Solar System, which, aside from Earth, is made up of some fairly unattractive real estate.

* TransportersAndTeleporters were cooked up entirely to keep from having a DropShip sequence from eating [[Series/StarTrekTheOriginalSeries a certain show's]] entire budget, and were [[MisappliedPhlebotinum consequently poorly-implemented.]] The device as described completely breaks both conventional physics and quantum mechanics as we currently understand them over its knee, but there's no story (or, at least, more [[BottleEpisode cheapo episodes]]) if the shuttle animations budget guzzles up the action sequences. Having the actors disappear and re-appear elsewhere in a cloud of sparkles is much cheaper

* TransportersAndTeleporters were cooked up entirely to keep from having a DropShip sequence from eating [[Series/StarTrekTOS a certain show's]] entire budget, and were [[MisappliedPhlebotinum consequently poorly-implemented.]] The device as described completely breaks both conventional physics and quantum mechanics as we currently understand them over its knee, but there's no story (or, at least, more [[BottleEpisode cheapo episodes]]) if the shuttle animations budget guzzles up the action sequences. Having the actors disappear and re-appear elsewhere in a cloud of sparkles is much cheaper

** Similar to AliensSpeakingEnglish, in stories where there is a lot of interplanetary travel, each planet is shown as having either only one culture, two cultures who are at war with each other, or, at most, three cultures consisting of two who are at war, and one who is below (like underground) or above (like super intelligent) it all. But if you just think about how many cultures there are on planet Earth, you see how unrealistic this is. But it's necessary, because otherwise it makes things too complex and confusing.

** ArtificialGravity, for "[[MohsScaleOfScifiHardness soft]]" ScienceFiction works (though otherwise "hard" film and especially television ScienceFiction will sometimes make use of it due to the extreme difficulty of producing true "zero-g" on camera).[[note]]Although, this may depend on how it's presented and achieved in-story. For example, just spinning the ship and having people walk on the side walls is perfectly reasonable.[[/note]]

* Blatant WishFulfillment and MarySue characters in {{Fairy Tale}}s and mythology.

* NoConservationOfEnergy in portrayals of StockSuperPowers.

Can often be the cause of an EnforcedTrope. Some AcceptableBreaksFromReality are Necessary Weasels to particular genres as well. Also compare the AnthropicPrinciple, where certain factors, no matter how improbable, have to occur for the story to happen. Contrast with the WritingPitfallIndex, an article listing tropes that can lead to real (versus merely perceived) flaws.

* CleanPrettyChildbirth in family friendly films. Most people do not want to see body fluids and other gross things during a birth, particularly during scenes intended to be heartwarming, and it usually is required to be omitted to keep the rating.
* ToiletHumor in comedies featuring babies or animals.

* CommonHollywoodSexTraits: Because ''real'' sex isn't always sexy, and a realistic depiction would likely go into IkeaErotica territory, most stories that feature sex or its aftermath are going to involve IdealizedSex.

* Many Christmas stories involving SantaClaus do not address or adequately explain {{Plot Hole}}s inherent in the premise, such as why no adults know he exists even though there are millions of toys showing up that nobody purchased, among other questions. Attempting to answer these questions may diverge the story too far from the classic legend, and most people who like Christmas stories are willing to ignore these issues.

* ImperialStormtrooperMarksmanshipAcademy - If the {{Mooks}} always hit their mark, the hero would be dead and the story would be over.

* ImperialStormtrooperMarksmanshipAcademy - If the antagonists hit their mark, the story would be over.

* Many Christmas stories involving SantaClaus do not address or adequately explain PlotHoles inherent in the premise, such as why no adults know he exists even though there are millions of toys showing up that nobody purchased, among other questions. Attempting to answer these questions may diverge the story too far from the classic legend, and most people who like Christmas stories are willing to ignore these issues.

* RubberBandAI: In various genres, but especially the RacingGame genre. Quite simply, if the player is able to trounce the AI, the game gets boring.

* FasterThanLightTravel: usually present in space-based ScienceFiction and virtually all SpaceOpera. Without it, you can't really go anywhere other than the Solar System, which, aside from Earth, is made up of some fairly unattractive real estate.

* JumpPhysics in {{platform game}}s.

* {{Infodump}}: Sometimes, the audience will need to know something critical before it happens and, while usually a lot better to try and work it into the story gradually and over its course before it becomes relevant, there are some situations where it's just not possible without bloating the main plot of the story overall.

* HistoricalHeroUpgrade: If every real or mythological historical figure was portrayed as accurately as possible, the vast majority of these popular figures would be too morally repugnant for a modern audience to root for.

* {{Dramatization}}/VeryLooselyBasedOnATrueStory: RealLife is not like fiction. There are many boring parts, there's no real story arc, often many internal inconsistencies and details that are confusing for outside viewers, and as noted above, some "protagonists" may have done stuff that would make it difficult to root for them if it ''were'' a story while "antagonists" are rarely as black and white [[HistoricalVillainUpgrade as fiction tends to make them]]. Changing details for stories supposedly BasedOnATrueStory are necessary to make them fit into a cohesive and entertaining narrative (although contention can come from ''how much'' and ''what parts'' are changed from real-life events).