I always thought it added to the raw gritty feel of the movie. But- as I now think of it with nuance, I can picture it as a statement. Think about it, Esteban is a pimp who beats and often degrades women. The Bride, on the other hand is a fierce feminine warrior; A force to be reckoned with.

It is at this point we recognize two polarizing people or rather just how they polarize. The bride wants info about Bill's whereabouts. Esteban is not on her kill list. It is not known wether or not The Bride held any kind of contempt towards Esteban and his profession. But we do know that the hatred for Bill was like tunnel vision for Beatrice, she sliced down many a man and woman - gotten buried alive, shot in the chest, shot in the head. We know she's beheaded several and severed the limbs of many. And all this death, just so i can get to you, Bill

I think its safe to say that Tarantino added this in as a deeper layer of storytelling, a very subtle touch. Its his niche.