I'll admit something--I'm a bit of a sucker for found footage movies.
A fairly recent phenomenon, found footage is a movie format that presents itself pretty much as advertised--the film is a series of segments of footage discovered after an event and pieces together as a cohesive narrative. It differentiates itself from the mockumentary genre by being almost completely stripped of anything that isn't so-called "original" source material.
While the genre existed occasionally since about the 70s--when "found" footage was at least someone practical with mobile video recordings--it really kickstarted with 1999's Blair Witch Project. But even then, there weren't a ton of releases--the Blair Witch sequel dispensed with it more or less altogether in favor of a more conventional film, and the 2000s didn't have much else to offer.
The current resurgence is owed almost primarily by the movie Paranormal Activity. Released in 2007, it went full on with the "found footage" concept. Now, we live in a world where literally everyone carries around a small video camera; nearly every computer and laptop has a built-in camera; and GoPros and similar small, durable cameras are cheap and plentiful. Before, stories had to justify some reason to be recording everything, including details that normally wouldn't; now, you could insert a camera pretty much anywhere and have it be at least someone believable.
Of course, the found footage market is almost wholly owned by horror films. It makes sense--for pretty much any other type of genre, there would be no need for "found footage"; the entire concept is built around the fact that at some point the footage was lost, presumably due to unfortunate circumstances. Only the worst dates would qualify a rom-com for that sort of treatment. (That said, a few other genres have tried it, such as science fiction or crime, to mixed success.) It also helps that shaky, blurry, and non-professional camera work lends itself to spookiness on screen. Finally, of course, the horror genre, already notorious for low-budget fare, can get even lower; with only a modest outlay of funds one can record a movie you can go to the theater to see today.
I'm not sure why I'm such a sucker for these sorts of films. I'm very hit-or-miss on horror; it's a genre I only have a passing interest in normally. I think maybe it's because these films are usually more about suspense then special effects or gore. Paranormal Activity famously had almost zero special effects for the entire movie (only the last few seconds had any CGI at all), and built its narrative around creaky doors, moving shadows, and creepy reactions. To me, the ability to scare the shit out of me using ordinary household items and dialogue is significantly more impressive than a CGI-laden gore-fest.
Of course, the format has its downsides. Because it's so cheap, there's a glut of them out there; over two dozen have been released in 2014 alone. It can sometimes be difficult to sort through them all to get to the good stuff. (Of course, due to the economics of the industry, even modestly successful straight-to-video offerings still turn a profit.) In addition, many of these films concede more than just found footage, inserting more special effects and music. And even though there's so much technology out there, it still seems to stretch credibility as to why there are cameras everywhere. (Paranormal Activity 4, in particular, had to cobble together about a half dozen different excuses as to why something was being caught on camera.)
Still, I think it's a genre that's here to stay, and I think the horror genre is better for it. After years of ramping up expensive special effects, elaborate justifications for endless sequels, and a limited scope, it's nice to see a little bit of creative efficiency in the market.