If you’re not familiar with the history of the term “fan service”—introduced and mainstreamed by anime audiences in the late ‘80s/early ‘90s—you might feel like observing contextual clues is all you need. This is how dilettantism, and the majority of pop-cultural criticism, works: You look around, see other people saying a thing, maybe-sorta-kinda figure out what it almost means, and then repeat it in the hopes of securing the same reactions.
“Fan service” is a derogatory term for a specific type of pandering. Historically, “fan service” only becomes fan service when the element in question is egregious and unnecessary. Stopping your story down to elbow fans in the ribs with metatextual, intertextual references; inserting gratuitous nudity that has no set-up or purpose other than instant gratification—that's “fan service.” The term is rooted in the idea that fans are often the worst barometer for good writing, and focusing solely on indulging them is an act of storytelling self-harm. So far, so good!
However, “fan service” is not simply “Here’s a thing people like,” and it’s also not “Obvious payoffs to beats previously layered into the narrative,” because making things people will like is one of the primary reasons people tell stories in the first place. This prevailing usage of the term is a bullshit sneer from a fronting fan who believes pleasing a crowd at all is an inherently lesser ambition: “Sure, that’s cool, if liking things is your deal, I guess....”
It seems imperative to many culture writers that fandom’s concerns be carefully addressed—a sop to the untrue notion that success without fandom’s presence (or worse, its input) is impossible. But fandoms are generally a relatively tiny and contentious collection of overzealous weirdos. Fandom isn’t a necessary endeavor at all—it’s an elective, religious minority whose frequent tithings are aimed not at theocratic bodies, but towards a (shrinking) collection of conglomerate entertainment brands.
And when any crowd-pleasing moment occurs in a story, these same culture writers—a hugely compromised wing of the already-weakened fourth estate—consider it an automatically debased feat of “fan service.” Are we so suspicious of happiness in these cultural times that its mere presence causes a cynical attack on the first hint of positive feelings like white blood cells murdering a virus? Probably!
But most of the enjoyable stuff in popular entertainment isn’t fan service, and calling it such doesn’t make a criticism smarter, more insightful, or culturally relevant. In many cases, it isn’t even really criticism, but naked presumption and self-aggrandizement: “When I like it, it’s good writing. When I don’t, it’s fan service.”
It’s a weird (and weirdly insecure) place to speak from, especially in the aftermath of 2019’s twin media behemoths: The 22nd sequel in an ongoing superhero film series becoming literally the biggest movie of all time, and the finale of the most popular television drama in recent memory.
Both Avengers: Endgame and Game of Thrones had plenty of moments called out as “fan service.” But nearly all of those moments served the story first, and not any supposed group of “fans.” This is what functional storytelling often does: Makes good on promises, brings closure to previously open-ended possibilities, and satisfies both character-and-audience needs. (Great storytelling often does those things in a way that simultaneously subverts, spins, or critiques those expectations while still maintaining strong emotional engagement.)
Which is why it's so strange to see “fan service” derisively bandied about when those stories succeed in those goals. Are Avengers: Endgame and Game of Thrones full of “fan service”? They aren't. (Okay, okay, Endgame is a little) Your mileage may vary as to how resonant the execution is, sure—but they're both stories that, in their best moments, conclude, stories that pay off, that reward, and in the process, see their creators justifying the time and effort invested by general audiences. That's not "fan service" That's storytelling.