If I somehow killed all Survivors with Devour - the Entity is displeased. WTF?!
When you kill people, you have less chases, less hits, less hooks. Meaning you score less points.
That's why it gets displeased.
The game rewards you for a longer game. This also applies to shorter chases, more hits, and generator protection.
If you just kill all the Survivors after getting the required amount of Devour Hope stacks to do so... you won't really be rewarded. Its like going in the game with a Ebony Memento Mori, you'll get nothing from it really unless you use it as a finish rather than using it when they get hooked once.
You don't get rewarded for killing the survivors. You get rewarded for baby sitting them and making sure they have a fun game and then killing them at the end.
@Aztreonam78 Basically what @Sairek said. You mainly have to just play along in order for the Trial to be anything other than a Brutal Killer.
If you're lucky you might get a Brutal Killer from killing all 4 Survivors with some minor chases in-between. Otherwise no, you won't be rewarded for speed running the match.
If you want to guarantee a double pip as killer you basically have to hook every survivor 3 times. No camping, no moris, no insta-downs, no slugging all the survivors before hooking them... you have to play them straight. I can understand it to a degree because that does take more skill. If you're using any kind an ebony mori or just killing a bunch of potatoes with devour hope, that doesn't require optimal skill to win. An ebony mori is a handicap. There's nothing impressive about winning like that.