Stargate Studios Virtual Backlot Reel 2009

You only notice the bad CGI - most TV shows, even a normal sitcom, have a ton of CG that you would never realize unless you saw the raw shots. It's what the audience expects and demands today. Things are getting more efficient but quality level has risen even faster. Here's a good video, from 2009: this video And 2012: link

Even today, there's good and bad uses of CG, usually coming down to schedule and creative direction. The average quality has gone up substantially, though. As you pointed out, there's all kinds of ways to use CGI and VFX more subtly that most people would never realize. this video is a great example of green screen set replacement being used for things as ordinary as a city street, 15 years ago on a TV series budget. I expect the use of AI will be similarly varied in the beginning. It could be used just for background details. It could be used in a hybrid fashion where artists design the characters with reference poses, a storyboard, and maybe even some keyframes, and the AI fills in the gaps. And of course some studios will just be sloppy and use AI to generate larger pieces without fixing the glitches and inconsistencies. People are sometimes dismissive of AI based on the "fire and forget" prompting modes but don't consider AI-assisted tools or human-assisted AI like inpainting.