There are just a lot of barriers put between the film and the viewer that damage the authenticity of the world they're trying to portray, which is typical of modern blockbusters.
Unnecessary CGI body doubles: On a subconscious level you recognise that what you're watching isn't in camera and doesn't look real. I'm not disparaging the work of VFX artists - they are amazing - but when they're used for lingering shots and the same action could be done with real people, the filmmakers are sabotaging the film's believability. There's a reason Fury Road was celebrated for putting real humans in perilous situations to achieve its action scenes.
Slow motion during action scenes: This highlights the artificiality of the film. Slow motion worked incredibly well in The Matrix, because it gelled with the diegesis of the movie. It was an artificial world. For something more documentarian, where a camera is meant to be an unobtrusive fly on the wall, all slow motion does is say to the audience that this is a trick, an effect. Granted, there was slow motion in T2 when the protagonists encounter the Terminator, but this was done to emulate the phenomenon of "events unfolding in slow motion", to convey their fear.
Ever more elaborate Terminators: Since T2, the practice of putting a few twists on the T-1000 and introducing yet another hybrid has always just come across as gimmickry. The T-1000 was a landmark for visual effects and his abilities literally couldn't have been filmed in 1984. He was surprising and terrifying. Today, the liquid metal/shapeshifting effect is very familiar and no longer that impressive. Lingering on these shapeshifting shots just serves to highlight the artificiality of the situation. A lumbering, unfeeling man with blood squibs would be scarier than seeing an elaborate CGI shot. At least your brain would acknowledge it as realistic and horrifying.
The Dark Fate of unlucky characters: Most successful films probably have one good sequel opportunity while maintaining the fictional world's believability, two at a push. The longer a franchise persists, especially involving the same principal actors, the more the events of the latest film stretch credulity. How many times can the fate of the world fall to this person? The Alien movies fell victim to this too, with Ripley's ascension from normal scientist to...badass clone. Movies like Mission Impossible and Bond just about get away with it because of the heightened unreality of their fictional universes.
Ever escalating stakes and setpieces: The further we've moved away from the small scale, grimy horror of T1, the more outlandish and unbelievable the stakes and setpieces have become. The climax of T1 involved navigated a factory. Here, we see our principle characters involved in a ridiculous, CGI laden spectacle on a plane, no doubt dodging all sorts of health hazards and surviving. And this probably isn't even the film's climax.
In conclusion, I don't know what I was expecting. I held out some hope based on that Q&A Miller and Cameron did a while back, assuring us that this would wash away the bad taste of the post-T2 films. Nope. They don't know what the fuck they're doing with this property.