A very sharp pointy nose doesn't serve a purpose on a board and many people have had an eye poked out. There's a good article about this in the Surfers Journal (21.4). The author claims that K. Slater cuts the noses off his boards. I have never been poked by the nose of a sharp board but have been sliced by a fin and sanded down my fins after the experience.
A sharp pointy nose does serve a purpose on a board. If there is less surface area at the nose you are less likely to catch the nose on steep drop ins. Surfboards basically undergo evolution.. If a design doesn't make sense it doesn't stick and you never see it. If it works, it's still around.
Its purely asthetic according to George Greenough, Bob Mctavish and other shapers. "The board (without pointed nose) will surf better because you have reduced the swing weight and wind resistance." According to Greenough.