The Blair Witch Project was innovative. I much admire it. But not most of the copycat films that have since tried to mimic its found footage formula. Of course, every successful horror film "inspires" inferior copycats -- and the occasional superior copycat. But the horde of found footage films since Blair Witch have been especially lacking in merit.
Is there something unique about the found footage style that encourages bad filmmaking? Yes.
The found footage style provides an excuse for -- and thus encourages -- laziness and low effort. In general, filmmakers know that strong production values usually make for a better film. But in the case of found footage, filmmakers often take less care with composition, lighting, or sound, on the rationale that, because the film is supposed to be a "home movie" shot on real-life locations, it makes sense that camera angles are rough. Lighting is murky. Shots are out of focus. Voices are muffled by wind and other noises.
Acting and writing also suffer on found footage films. Actors, without talent for improvisation, will nevertheless improvise their dialog (poorly), on the rationale that they should sound like "real people." Well, real people are boring, their dialog a disjointed series of vapid non-sequiturs. Talented screenwriters know that dialog should sound real, but not be real. A script should evoke verisimilitude -- the semblance (not the actuality) of reality.
It's not that a found footage horror film can't have great production values, writing, and acting. (The Last Exorcism and Quarantine prove otherwise). It's that the found footage style tempts a filmmaker to slack off. To ignore poor lighting and bad sound recording. To convince himself that his inanely babbling actors reflect a raw authenticity.
But rather than capturing an engaging vérité authenticity, the final film often feels lazy, sloppy, and dull. Padded scenes with interchangeable characters, chattering about trivialities while waiting for something to happen.
Found footage doesn't mean you can ignore writing, acting, and production values. Audiences still want a strong story told at a fast pace, engaging characters portrayed by talented actors, sharp dialog with witty lines, and all the rest. Not some amateur "actors" wandering about an allegedly haunted ... whatever ... improvising empty dialog, until something evil (that we've already seen in previous films) finally strikes.
For more information, see Horror Film Aesthetics: Creating the Visual Language of Fear. This blog represents a continuing discussion of my views on horror, picking up from where the book left off.