Arteta should be given more chance for me he is still doing well as Arsenal manager despite not winning English premier league tittle but they are making progress to that every season and if they continue been consistent like this they will one day be the English premier league champions with Arteta, if not for their inconsistency towards ending part of the season Arsenal would have also won the English premier league with Arteta.
One thing you should also know is that in football ones the team is not doing well they put the blame on the manager if a team is also doing well the manager will be the one to eat the glory so that's just the nature of football.
The same thing was going on my mind, I can see why Arteta should stay at the club. While I am not so sure if they are going to win the league, I can tell you that they are doing better than any other manager could make them. Obviously if they hire someone like Pep, Ancelotti, or even convince Simeone somehow etc, they "may" do better.
However, what they have right now is already good so it doesn't feel like we are going to end up with a bad result, it just doesn't feel like it's a bad decision to keep him. We are seeing them do fine, so they should keep him, not because hey may win the title, but because anyone else could be a lot worse, those are the important decisions, the aim isn't to be first, the aim is to avoid to be fifth.