I don't recall how he was written in the original novels, but in the movie, Carter comes across as self involved and just driven by greed, to the extent he comes across at all. Without a strong lead character, there's no hook for the story.
I get that the idea is, he's damaged and searching for meaning, or something like that, but for a motive like that, you'd need someone with a lot more screen charisma, like a young Harrison Ford. The writing doesn't make you immediately like the character, so the actor needs to take up the slack.
That's what made the miscasting so fatal - its a harder role than it seems at first glance, and much harder than something like a superhero movie, where the character's motive and reason to like him is shoved in the audience's face.