Whenever the film industry tries to make a film based on a cartoon or "cartoony" game character, they always feel the need to change the design so the character can "fit better" in a live action environment. I understand that mentality, to a degree; if you had to adapt a cartoon into a live action film you would want to integrate the character into the real world as best you can. However, "realism" isn't always the best option and a more "cartoonish" design can make people connect more with the character.
One of the best examples in recent memory was for the video game film "Sonic the Hedgehog". When the trailer first hit for the film, it was lambasted with criticism over the design of the title character. The famous video game character was given semi-realistic human lips, teeth, and muscle structure that clashed horribly with the inherently "cartoonish" elements of Sonic's famous design. The original design was so criticized that they had to push the film's release date back and completely overhaul the design. The final design hues closer to the original game design and benefits from it. The final design can display more exaggerated facial expressions more effectively which allows the audience to better empathize with him. He also just looks a lot cuter in action.
Another example comes from another video game movie "Detective Pikachu". The film was one of the first to bring the exaggerated cartoon designs of Pokemon to life in live action. To this day, it serves as the best example of how to translate cartoon characters to live action. The design, color, and proportions are all kept accurate to the characters in the game and cartoon. The realism comes in the texture of their forms. Pikachu is given realistic looking fur, Charizard is given dragon scales to match his form, and Magikarp is given realistic fish fins and slimy texture. They may not be designed to look like real world animals, but they have the texture of real world animals so they "could" exist in the real world.
One final example comes from the live action Transformers films. The original films stepped away from the simpler designs of the cartoon and created more complex designs for the Transformers. They were given sharper features, more complex moving parts, and strange looking facial features to make them appear more "realistic" and alien compared to the cartoon. However, these designs are an aesthetic nightmare. It's hard to tell where body parts begin and end (especially on Ironhide) and almost all of the Decepticons have military aircraft vehicle forms, which makes them all colored gray and hard to tell apart. Contrast this with the spin-off film "Bumblebee" and you can see the difference. That film had simpler designs closer to the cartoon, which made them more colorful, and therefor easier to distinguish each character.
The lesson to take away from all of these examples is that realism isn't always the answer. Photo realism is fine in many cases, except when adapting cartoon characters with inherently "cartoonish" designs. What people often forget is that it's the less realistic aspects of a cartoon character that create empathy (large eyes, big smile, etc.).
