Why is obierika sometimes sorry he has the title of ozo?

Okonkwo begins to feel better, and he leaves to tap his palm trees. Only men without title are allowed to climb the trees to tap them, and Obierika says that he wishes he had not taken the ozo title sometimes, since it pains him to see inexperienced young men killing the trees in the name of tapping. Okonkwo defends this as the law of the land, however, and says it is good that their clan holds the ozo title in high esteem.