Word is out that with the setting up of a sequel to one of the few horror films in recent memory that was not based on an existing Japanese film, Rogue Pictures wants to turn The Strangers into a horror movie franchise not unlike Saw or Hostel. (Source: Variety) I think that if they did that, it would be a completely terrible mistake.
The beauty of a horror movie like The Strangers is that you really have no idea why the antagonists are going around killing people; you only know that you’re supposed to cheer against them and cheer for the protagonists. It’s good versus evil in its truest form, and no matter who wins you know that it’s going to be pretty satisfying. Remember The Birds? Not even in the original short story is it ever really explained why the birds have all gone on this murderous spree, and that’s perfectly okay. You also only need to watch The Happening to know that if you try and explain something a perfectly weird phenomenon, you can get a pretty crappy movie as a result.