The main difference between arbitration and Court is party autonomy. In arbitration, the parties call the shots on how the case is run. In Court, the Court determines how the case is run.
Courts have an excellent track record in achieving justice. Judges and Juries do a great job. Massive litigation such as class actions should be in Court.
A majority of litigation, however, is better off in arbitration. It simply takes too much time, money and procedure to get in front of a Judge.