Here's a reply from a CG generalist:

"Typically, design is worked with the client. VFX is a service industry, IE McDonald's. You want pickles on that, we add pickles. Eventually though, and because VFX doesn't really have stopping power, clients who lack vision (IE most of Hollywood) can just… Ruin it.

So, in the case of Sonic, or Cats, or anything bad, it is usually the clients fault. For example, MPC is the studio making the vfx for sonic, but they also did Jungle Book, Lion King, and Bladerunner. These guys are extremely good artists. The difference, every time, is client.

VFX is full of very talented, but overworked people, because we are bogged down by very silly stuff like set fixes, production errors, etc.. Because, once again, it's cheaper for us to fix a mistake that they could have on set because we are non-unionized.

It's hard to see when we do our jobs well, and really easy to see when we are overworked as well. I'm not saying there aren't bad vfx out there, but I am saying that most of the time, especially on this scale, it's a problem of time and money and burnout. I appreciate you asking!"

TL;DR: Executives run the non-unionized workers into the ground with terrible and creative decisions.

My theory at this point is there's only a set number of good VFX people in the industry and they all worked on Detective Pikachu this year.