What wouldn't be known about Juliet if the nurse wasn't there?
Without the Nurse to tell the tale, the audience would not have known that when Juliet was just learning to walk, she fell and got a large goose-egg on her forehead. The Nurse tells the punchline to the story at least four times about how her husband laughed when Juliet fell down and how he'd said that she'd fall backward when she "had more wit". Baby Juliet's resonse had been "Ay", making the Nurse laugh all the more at the tale. The audience would also not be aware that Juliet was born on August 1 (Lammas Eve), and since it is a fortnight till Lammastide, then the play is set in mid-July. The Nurse also mentions how she had also acted as a wet-nurse to Juliet after the death of her own daughter, Susan. Apparently, if she were the one feeding Juilet, the young Capulet child probably bonded with the Nurse more than with her own mother. It seems that this is true based on the fact that Juliet confides in her about Romeo and not in her mother.