It makes the song have a more dance and party rhythm. Basically it makes the song more fun to dance to and like I said some people add beats into the music to give it kind of a mix of dubstep as well. I just don't know how to do that yet. Plus changing the pitch changes the tune and whereas some people may not like the tune of a song that might be like country, it won't sound country after it has been put into nightcore mode and they would maybe like it better. In basis, it adds a club music feel to it.