Totally disagree with and do not buy the defense of this style/degree of violence entirely serving the narrative/thematic purpose in the case of a game like this.
If you enjoy or do not mind the visceral hit of hyper-violence, that's one thing, and that's fine, I can understand that as a guilty pleasure perhaps, but who are we kidding with the reason for it? For the most part, people just enjoy the superficial exhilaration of being thrown into an intense life or death situation where the relentless brutality is just meant to satisfy a sensational hit/shock-value high that needs to get more and more extreme the more that we get desensitized to it. It's not REALLY fully about meaningful or necessary high-stakes realism serving artistic purposes (to some degree, sure, but it's not a coincidence that you don't see many actually artistic movies pull this kind of stunt nearly as relentlessly-- it's usually more of a "less is more" usage of violence that is most lastingly effective), most of it just feels like pornography that wants to be as immersive and believable as possible so that it stings harder (not that there's necessarily anything wrong with enjoying a game on that level, I guess). And it kind of makes it so that all of the thematic stuff that is meant to justify this kind of thing just end up feeling like a bit of an infantile excuse to have a setting that allows them to focus on throwing as much of that in there as they can (and appealing to the visceral demand of gamers). Any meaningful themes and ideas are actually somewhat cheapened by this approach, not elevated by it, if anything, IMO.
Even the first one was kind of like this, on some level-- this just turned up the dial to a degree that makes this more superficial motivation seem a little more transparent and obvious. Certain television dramas and movies aimed at younger, teenage/college-aged people have a tendency to do a similar thing.