I've been watching the terminator films a lot recently (of which there are only two BTW), along with their counterpart making of's and the practical effects still hold up, especially in the sequel. They use so many techniques, each involving their own distinct craft, and the final scene in T2 is like a grand celebration of analog movie magic. Within a 5 minute time-frame you get see the use of stop-motion, rear screen projection, huge explosions, advanced prosthetics and make up, miniatures, image overlays, puppetry, CGI, and last but not least, the mind-bending shit that stunt pilot was doing in the helicopter, flying up and under fly-overs at high-speed like a complete maniac. It's fucking wonderful spectacle to behold and the array of disciplines really blend in and merge to the point of complete immersion. If that film was made today it'd allllll be in CGI, and it'd be a more generic, bland and lesser film overall as a consequence.
That's the problem with the CGI slosh you see whizzing around on the screen now. You mind knows when it's being played, and the CGI, even after all this time, is still detectable. Unless used correct and not overdone (see any Marvel film for reference), it takes me right out of the film. I know none of what I'm seeing is real, even basic structures or background imagery, and all I'm looking at is a roided up bloke in spandex play-acting with a toy hammer in front of a green screen.
Take a look at the final scene of the original Terminator, where it's just an janky exo-skelton chasing Sarah and Kyle. The fact that it's low-budget stop motion adds to the tension and sheer terror (which is what all good sci-fi should do. Provoke a sense of awe as well as terror simultaneously). If it was done in CGI nowadays they'd be making it do cartwheels and backflips and all sorts of stupid, unnecessary shit.
The best CGI is subtle background enhancement, like the crowd-scenes in Gladiator. That's when it's utilised best because you don't notice it. As much as a genius I think James Cameron is, I think his over-reliance on CGI will cost him, making these films just seem like another generic, run-of-the-mill movie.