The nose is like a pyramid, if you rasp the nasal bones the top of the pyramid becomes separated, so that the tissues that drape the nose (the skin) looks blunted and not as sharp, so the nose looks less projecting and appears wider. To overcome that, Plastic Surgeons for decades have been "breaking the nose" by gently infracturing the two nasal bones, so they reform the top of the pyramid. That is why was have to break the nose and why the patient has to wear a cast for 7 days, while the nose heals.
When rasping the front part of the nasal bone/dorsal hump more than a millimeter or 2, it will create an open roof deformity and the nose will appear wider. Osteotomies of the nasal bones are then required to narrow the nasal bones once the hump has been removed. For more information and many examples, please see the link and the video below