1) New York is one of the most important and popular cities of the world, for different reasons. You can visit a lot of historical monuments, and learn a lot about the history of America. Moreover, New York is a fashion city, which means you can go shopping everywhere. If New York attracts so many tourist every year, it's because there is always something to see for every single person.
2) Since New York is a very important and famous city, a lot of movie scenes are turned in the city which never sleeps. New York is a place where every one can find its own personnal spot. You can go shopping on 5th Ave. you can go to Central Park, or learn more about history. This is why New York is one of the favorite locations of Hollywood. You can do everything in New York.