I felt the duel was pretty much the whole point behind The Phantom Menace. It's the Jedi's first real battle in thousands of years, and the only unsuccesful part in Palpatine's plan (as he was forced to find a new apprentice).
But back on Jar Jar, it has occured to me that instead of being banished he should have escaped the city. With the Gungans being so perchant to war, Jar Jar could be established as a pacifist that left because he didn't want to join the army.