Why? Because they deserve to be.
Created by writer/editor Stan Lee and artist/co-plotter Jack Kirby the Fantastic Four appeared in November 1961 and as the first superhero team title produced by Marvel Comics. It helped to usher in a new level of realism in the medium and formed a cornerstone of the company’s rise from a small division of a publishing company to a pop culture phenomenon.
The team is much more than a group of people with superpowers. While the Avengers are a super-powered unit with great banter, the Fantastic Four really are a family. This is solely the reason why it would work with the MCU. There has always been family tension within the group, as neither member is totally comfortable with their roles.
The Fantastic Four deal with Reed and Ben’s conflicted friendship, as Reed feels guilty for Ben’s transformation, Sue struggling to persuade Reed to have some empathy, balancing it out with logic, Johnny’s desire for fame, Ben’s anger and self-esteem issues, and even with all that tough exterior, he is a giant softy at heart. The dysfunctional family element can be played up extremely well, something the 2005 film did a decent job on, but the problem was that it was the main theme of that film. Fantastic Four is a story about fun adventure that includes a dysfunctional family that battle monsters and overcome their internal conflicts with each other. Not to mention Reed and Sue eventually have children Franklin and Valeria Richards, both whom have superpower abilities.
While the X-Men, Avengers, and the Justice League have roster changes, the Fantastic Four by its very nature is solely tied to Reed, Sue, Johnny, and Ben. The team are exclusively identified by their members. If one is missing or leaves, the entire team dynamic dissolves. Yes, they’ve had temporary members, but no substitute has ever been able to fill the shoes of the original member.
The team also gets involved in many space explorations and other intergalactic universes. The comics were more than just a series of villain of the month tales, they were more-so the Star Trek of superhero comics. It would always be Reed who involved the rest of the team into space explorations. Much of his arc is tied into sci-fi elements, and most of the time he takes to too far, almost slipping away from humanity, only to be grounded and saved by Sue Storm. Without her, Reed would absolutely turn into another Doctor Doom, and he is wise to see this himself.
Speaking of Doctor Doom…it’s a travesty that every cinematic portrayal of one of Marvel’s greatest villain butchered and trivialized in every single attempt. Doctor Victor von Doom is the pinnacle Earth bound Marvel villain and is an icon of comic book villainy. He belongs in the hall of fame of super villains, and for those who don’t know the importance of his villainy, consider him in the same realm as Thanos, Ultron, Loki, Darkseid, and Lex Luthor.
Doctor Doom is just one of many villains the team has faced off. Let’s not forget Galactus, Silver Surfer, Namor the Sub-Mariner, Mole Man, Annihilus, and the Skrulls! There are endless assortments of characters to choose from. Their stories were a spawning ground for many other strange and great characters. Spin-offs were developed starring many of those characters such as The Inhumans and even Black Panther who first appeared in the Fantastic Four comics.
Who would want to see this team interact with other MCU characters? Any fanboy would love to see Reed Richards, Tony Stark, Bruce Banner, and Hank Pym, the brainiest superheroes all in one room and talk about their girlfriends/wives and science mumbo-jumbo. Bringing in Sue Strom also brings in more female super powered heroes within the cinematic universe, which is a plus. She is the glue that keeps the team together after all. On top of that, a bromance with Johnny Storm and Peter Parker would be exciting and a sweet cherry on top would be the Thing vs Hulk. Come on, how does that not sound appealing?