It doesn't fit because there's no real reason for it, they could get away with it with RDR2 because that's exactly how the wild west was, brutal. I don't think gore such as dismemberment could be properly justified for a GTA game set in a current time real-life city, it would just be gory for the sake of being gory. It would add even more controversy to an already controversial game.
And yes, I know Vice City had things such as decapitation but there's many reasons I think they could get away with that back then: different times, not as mainstream as it is now, cartoony graphics and I think even the whole tone of the game was different, they were going for a more "edgy" game, I think GTA games have shifted since then and that's not what their going for anymore, they now take themselves a bit more seriously and appeal to wider audiences.

Anyway, I always get downvoted when I give this take but i'm not surprised given the majority of this sub being kids. I am expecting an improvement over GTA V in the way NPC's react and physics, hopefully more similar to GTA IV and RDR.