When people go broke sometimes they sell stuff they end up regretting later same thing happens to characters. Back when Marvel wasn’t making bank. They sold the film right to some of the beloved creations. As they began to dominate the box office with the creation of Marvel Cinematic Universe (MCU) they tried hard to reacquire their superheroes and villains they’ve had Spider-man back in the house but there are still many fan favorites that they’re unable to use.
X-men despite being one of the most popular comic book franchises in history it’ll be a cold day colder than ice man in the snow storm before we see any of the X-men hang out with or battle alongside a member of the adventures.