Good filmmakers can make the most of technical limitations. The CGI being used sparingly alongside animatronics, often in low light scenes, helps to connect everything to the scene and keeps it looking immersive and scary.

That's part of why Jaws worked so well as a horror movie. The shark animatronic was always broken, the water and robotics didn't mix well. As a result, they had to use the shark less, which brought up the tension more.

Compare that to something like Ghost Shark or another schlocky shark movie. There's no dramatic tension at all (although that's kind of the intention) because you just see the full shark as much as they want to show it.

The implication you don't see is scarier than the reality you do.