In primary rhinoplasty (a nose that has never been done before), grafts are used to help define the nose, especially noses with thick skin, and create a stronger nose as well. In other words, if a patient's tip cartilages are weak and bulbous, cartilage grafts can change their shape to make them structurally stronger and give a more defined look. Some weak cartilages are bulbous because they are very round and a cartilage graft can help make them less round and more straight, while at the same time strengthening them.
In older rhinoplasty procedures, more cartilage was removed and over time, this resulted in areas of collapse. With cartilage grafting, less cartilage is removed so the nose is stronger. Instead, the shape of the patient's cartilage is changed and made stronger, rather than excised. Also, some nasal tips have no projection and are too round and a cartilage graft (tip grafts and columellar struts) may be necessary to provide more projection and definition.