The Adventures of Tintin are liable to come across as cliché to younger modern readers who've read other adventure comics. Much of the comedy is also Slapstick, which was popular in most comedic genres, including film, when Hergé debuted, but now can come across as being corny.
Most Underground Comics fall in this category as well. Back in the 1960s and 1970s these comics were seen as edgy, subversive and dealing with topics most other comics didn't deal with, including sex and drugs. Nowadays in a time where even animated sitcoms like The Simpsons, South Park and Family Guy feature extreme violence, sex jokes and political topics, one might wonder what made these comics so special in the first place?
Donald Clarke, a film critic for the Irish Times, and other critics cited this as a flaw with the Watchmen film adaptation: Twenty years after the original graphic novel started the trend, deconstructing superheroes and showing them acting like real people with real personalities no longer seems like anything new. He used the example of the Parr family in The Incredibles by means of comparison.
Throw in Squadron Supreme as well. It actually beat Watchmen to the superhero deconstruction idea.
Or Bill Willingham's series The Elementals, which came out a year before Watchmen and The Dark Knight Returns.
Some of the "What If?" aspects of The Dark Knight Returns can feel a bit stale today, as they've since been integrated into the Bat-mythos as official canon. Specifically:
Having Batman and Superman forced into a battle to the death was shocking in 1986, since the two had always been portrayed as the best of friends before that. Since then, the stark contrast between Superman's idealism and Batman's pragmatism has become an essential part of their character dynamic, and it's traditional to depict them as complete foils who have difficulty trusting one another.
The revelation that Jason Todd was killed before the events of the story held a lot more weight when the book first came out, since the character's death hadn't yet happened in the regular comics (A Death in the Family didn't come out until 1988), and the idea of Robin being Killed Off for Real was still unthinkable to most readers. Now that Jason has since died and been resurrected as a badassAnti-Hero with his own series, hearing Batman angsting over his death can cause some eye-rolling.
Though a minor point, the inclusion of a female Robin, Carrie Kelly, doesn't seem quite as unique and daring now that Stephanie Brown has since served a brief tenure as Robin in the main DC Universe.
The depiction of The Joker as a mass-murderer (complete with the story casually slinging around triple-digit numbers as his supposed body count) with strong Foe Yay overtones toward Batman also originated with this story, as did Batman's internal angst over whether his Thou Shalt Not Kill code meant that he was responsible for every person the Joker has killed. All of these elements are largely taken for granted in any modern Joker story (granted, the Joker did kill people before The Dark Knight Returns, but the level of seriousness with which those stories - and Batman - took those murders bordered on Angst? What Angst?).
Being an Unbuilt Trope of the Nineties Anti-Hero, Watchmen seemed especially poised to suffer this. The chances of getting lost in the myriad of imitators when the original wasn't even being played straight seems very likely (since all the imitators just zoom straight in for the most obvious traits while the Unbuilt TropeMaker is trying to make a point that didn't really exist before; ultimately while not having the same intentions, they result in looking similar to the untrained and unknowing eye).
The Authority was revolutionary for its violence and political themes. Today, it fits right in with most modern comics.
The Dark Phoenix Saga. Before Jean Grey's death was retconned a dozen different ways and the concept of "dead is not dead in comics" became a punchline for critics and comedians, a story where a main character becomes a morally grey antihero who sacrifices herself to save the lives of her team was virtually unknown in comics. It's become almost commonplace to kill off superheroes in "event" storylines these days (to the point that some comic fans take bets to see how long the character will stay dead). To today's average reader, Jean's death isn't all that shocking.
Deathlok. The comic book character debuted in 1974. In 1974, the idea of a man who has been turned into a cyborg and struggles to keep his humanity while fighting against those who transformed him was relatively fresh and original. Nowadays it seems clichéd, and like a ripoff of Robocop and many other sources.
Doom Patrol. Very shortly after Fantastic Four debuted, Detective Comics tried their hand at "superhero angst". It was also the first title to pull a Kill Them All ending for the entire team. Now, it's more or less known for the youngest (surviving) member, who went into the Teen Titans, and for Grant Morrison's surreal early 90s run.
The Fantastic Four are considered by some to be the lamest Marvel superheroes out there. But, they were also the characters who introduced the concepts that revolutionized the genre in the early 1960s. It was unimaginable for readers back then to have a superhero with a monstrous appearance like the Thing, or dysfunctional team dynamics (that became so popular, the FF looks normal in comparison with most other groups). That's not to mention the villains, which included a dangerous leader of a foreign country and a planet eater entity bound to destroy the universe. And they didn't have secret identities, which were a staple for all superheroes then (and are still common even today).
Legion of Super-Heroes. The Great Darkness Saga is considered one of the all-time best Legion stories. The villain is Darkseid—a plot element that seems trite nowadays because of Darkseid's overexposure. But the story is from 1982, when that was a new idea - back then, Darkseid was a very obscure character who showed up in a low-selling comic from a decade ago.
Spider-Man was a unique deconstruction of superheroes when he was first created. The idea of a superhero who was a normal teenager like the readers and who had a normal life hadn't been done before. Nowadays, this is nothing special.
"The Night Gwen Stacy Died". Today, especially with The Dark Age of Comic Books, it's not rare for characters to be killed off left and right, but back then, the thought killing off such a beloved and popular character was unfathomable. It's often credited with ushering comics into the Bronze Age.
The series, along with X-Men, also first popularized the idea of superheroes who weren't wholeheartedly embraced by the public, and often faced fear and suspicion from the people they were protecting. The idea soon spread to the rest of the Marvel Universe, and even to DC.
Both the X-Men and New Teen Titans were revolutionary for the time, and set the gold standard for angst, melodrama, and Soap Opera elements in superhero comics. Nowadays, it's quite hard to see what was so special about the books, as it seems like an unwritten rule that every superhero team book must contain a copious amount of Love Triangles and angst.
The Disney Ducks Comic Universe comics of Carl Barks. He invented most of the characters and concepts, most notably Scrooge himself, and is regarded as a classic by people old enough to have the right kind of perspective, but these days his comics don't really look that different from those not-very-high quality same-old-same-old stories the average Duck artist produces easily and constantly (except maybe slightly dated compared even to them), and the few modern innovators, particularly Don Rosa, who himself adores Barks, have moved on to somewhere quite different. Rosa builds a lot on Barks's ideas, but Rosa's comics look much more impressive on a technical level, and the themes are treated in a way that allows them to be taken more seriously.
Back in the 1980s, Crisis on Infinite Earths and Secret Wars were big stuff. While characters had crossed over with each other before, earth- and universe-shattering perils so huge that not just one or two, but every single superhero (and villain!) within a given publisher's universe had to combine forces to defeat them was novel and exciting, completely unknown. Nowadays, the Crisis Crossover is a standard part of the superhero comic book publishing schedule, with at least one big event (sometimes more) happening every year, with the result that going back to the originals can be an underwhelming experience.
The early comics of Jack Kirby and Joe Simon have a layout that was revolutionary at the time but is par for the course nowadays. Back then, comic books were very unimaginative in their layout. They looked as if they were reprint collections of newspaper comic strips even when they weren't, with one strip above another. The idea that you could do splash pages, or have one panel take up half a page, or use diagonal gutters and odd shaped panels... All these things were completely new at the time.
One minor example from the pages of Superman: Brainiac's name. To many non-fans, or just casual readers who like the character but find his name laughable, it can seem a bit ridiculous to name an ostensibly serious supervillain after a juvenile slang word for "genius". It can seem that way... unless you know that the character actually came first, and that the writers of Superman are credited with coining the word. The fact that the word is now part of the popular English lexicon, and that most people who've said it aren't even aware that it's a Superman reference, is just a testament to the comics' ubiquity.
Pretty much all of Marvel's Silver Age comics are a little underwhelming. Yes they are competent, serious, fairly well-constructed and have decent stories, but there doesn't seem to really be anything groundbreaking here... However if you read the DC comics from the same time period (which displayed the worst excesses of Silver Age silliness) you can understand why Marvel made such an impact.