The padawan haircut is the Jedi equivalent to the medieval monk's tonsure. Keeps them humble. Gotta give these beautiful young people with psychic powers and laser swords a busted ass haircut to make sure they get absolutely no play so they concentrate on their studies and training and meditation. A sort of chastity belt, if you will. The fact that Obi-Wan and Anakin both got pussy with that look was an act of the Force itself