While is western cultures piercing is considered a rebellious act, in Hinduism it is a symbolic tradition. In Hinduism, it is tradition for a bride to wear a particular set of ornaments and the 'Nath' or 'Nose ring' is a very important part of the jewelry she takes to her in-laws' house. Since ancient times it is a tradition that the woman can keep the jewelry she got for her wedding only for herself, while everything else becomes her husband's. Expensive jewelry was given to a woman so that in case of need she could take care of her and her family.
The nose ring is also one of the several symbols of a married woman. In a few regions a girls nose is pierced once she is ready to get married. This tradition is regional and not all Hindus follow it. The other reason to have a nose ring is given in Ayurveda. According to Ayurveda, it is believed that a hole in women's left nostril can help her to bear the pain of childbirth.
It is surprising how a small tradition can show the diversities between cultures of the world. In one culture it is considered auspicious and is considered good for scientific reasons, while in other it is seen as an act of rebellion against ones parents and considered improper and wild.