It's hardly limited to FOX. See iZombie or Beauty and the Beast on the CW, or Person of Interest on CBS, or Grimm on NBC. Even shows like Constantine on NBC and Agents of SHIELD on ABC started out with procedural, case-of-the-week formats. Even Orphan Black started out looking like a cop show before it veered into something far different.
The thing is, cop shows and procedurals are what quite a lot of viewers want to see. They aren't so popular because the networks are forcing them down the throats of an unwilling audience; commercial TV doesn't work that way. They're what the vast majority of the viewing audience eats up. And network execs are in the business of making money, so if you want to get them to put a show on the air, you have to convince them that it will have appeal to the large, general audience that prefers safe, formulaic procedurals. So even if you want to do something weirder and more innovative, you need to work in that more comfortable, crowd-pleasing procedural angle.
But here's the thing: A lot of shows these days start out looking like safe, comfortable procedurals for the first few weeks, as a soft sell for the general, conventional audience and for the network suits trying to appeal to same. But after those first few weeks, once they've gotten the audience invested in their characters and situations, they begin drawing the viewers in deeper, adding more novel and challenging elements and veering the story away from that procedural format. So we can't assume that a show that pitches itself as a conventional procedural intends to stay that way indefinitely. That may just be protective camouflage to draw in the general audience before springing the really clever stuff on them. Person of Interest is a prime example. Even to this day, there are people who assume it's just an ordinary crime drama with a twist, because its procedural camouflage is so strong. But it's really a compelling work of hard science fiction about the technological Singularity and the emergence of superintelligent AI.
To be fair, though, I've heard an interesting theory from fellow TrekBBSer David Mack about why procedurals are so popular. As I recall it, the idea is that viewers tend to be more invested in stories about people who solve other people's problems than in ones about people who are just dealing with their own personal soap opera all the time. They like to see people helping other people, and that means cops, federal agents, private detectives, doctors, lawyers, superheroes, and the like. And a case-of-the-week format means that the heroes actually get to accomplish something every week, to build up a score in the wins column, whereas otherwise they'd just be wrestling with their own ever-worsening personal problems and never really gaining anything. So there are good reasons for including a procedural element in a show.
The thing to remember, though, is that the procedural format is just a framework for a show, not a limitation. It's just the basic structure of the work, like choosing to write sonnets rather than free verse, or to paint landscapes rather than still lifes. There's still endless room for individuality and innovation depending on what you build on that foundation.
