These days all Hollywood seems to be obsessed with remakes of old movies or movies "based on X."
Some are good, like Dredd, but mainly we seem to get stuff like "Battleship, based on the boardgame." (And Spiderman movies keep starting all over again... Much like there are three continuities of Batman movies, plus all the cartoons that are also separate continuities...)
I for one am willing to look at the Ghostbusters as a "new" movie rather than a sequel if they are trying to make it such.