If we’d gotten even a minute of broom boy in the Casino Bight scenes his ending would be much more defensible.
Um… what?
I’m saying that his part in the movie was rushed, just like the rest of Casino Bight. Just because it’s essential to the theme of the movie to place a character with little plot significance into strong focus in the final shot doesn’t mean that he shouldn’t have an arc. For example, when we are first introduced to him tending the animals, his abusive master could have knocked him to the ground and broken the Luke Skywalker toy, where he abandons it in shame. Then we would have all of the pieces of his arc in place after Rose and Finn restore his faith in the Resistance and the Jedi, and we’d see the repaired figure at the end. It doesn’t take much.