When I was 20 hours in I had barely scratched the surface. No offense but if you haven’t even beaten chapter 4 you’ve really got no business criticizing the character development in the game, as you haven’t even reached the primary conflict. It’s like watching the first half of The Godfather and asking why Al Pacino isn’t a full blown gangster.

All I can say is that Arthur keeps a lot of his shit bottled up due to his implicit trust in Dutch, and that includes his feelings about Micah. And a lot of that contempt spills out—for a variety of reasons—as the story goes on. The events of the Strawberry mission, in conjunction with the rest of the story, has a lot of bearing on the overall story. There’s a lot of build-up to that fact, which you likely haven’t reached...but it is there.