Speaking of Marvel movies, I really hoped for a better backstory for Cable in Deadpool 2. He was just this random badguy dropped in when he's SO much more than that. The Deadpool & Cable stories where Cable's trying to make a sanctuary island shows SO much character growth for the pair of them.
Like, Wade's more than just jokes and Cable's not just a super soldier. They bring the best out of each other and both realise they can actually be at peace with time.
I get you're condensing everything for a movie and trying really hard to fit huge books in a 2 hour timeslot, but I think with Cable, they really made him generic.