Though keep in mind, VOY, DS9 and even ENT had way, WAY less vfx shots than any of the new shows - it's easy to spot some shoddy cgi when there are a hundred shots per episode, and dozens of them were made extremely rushed to meet a deadline. Old Trek often had only one or two new vfx shots per episode.
Also, back then they were strategically hiding their models - backlight, viewed from afar, steady camera. Modern cgi often has the camera swirling around and going from wide shots to super close.
It's the same reason the dinosaurs in the original Jurassic Park still look better than in the new ones : Hiding them in the dark of the night, obscured by rain, and mixed with actual models. The newest Jurassic World has vastly superior vfx. Theoretically. But they're shown too much & too close, so that the seams suddenly become visible. I feel somewhat similar here. Not dunking on Trek specifically. I think a lot of modern vfx has that problem. But also we're just getting a shit-ton more cgi and just become used to it.
Yup. That is the biggest problem. They cram the scenes way to much nowadays. The Avengers films, transformers films etc. Are also good examples of this.