Why would WCKD use Grievers?

Question

In the Maze Runner, WCKD wants the kids to escape the maze, but they have made it almost impossible to do so because they have Bio-Tech creatures called Grievers created by WCKD patrolling the maze at night, but when kids go into the maze but they don't come back alive if the doors closed, that's saying something, but wouldn't they send something else instead of Grievers in? I understand they want to map the the patterns of the killzone in the kids brains and their immunity to the flare, but to kill them while in the maze? surely WCKD would want them to live and save humanity rather than be murdered by a gigantic maze.

What I'm trying to say is: They could have picked a creature that wounds the kids but not kills them so why didn't the organisation do this instead?

Answer 1

Unlike the books, the movie Gladers are numerous. Enough that WCKD can use them as cattle, as human donors and suck the enzyme out of their brain. We see hundreds of kids in the compound in the scorch trials. Killing a few kids isn't a problem. Not that we know they died. The kids the Grievers kill are never shown dying on screen. They could just as easily be non mortally wounded and captured. Since it happens off scene we can't tell.