Perfection in the digital world
Two vaguely related thoughts:
In real life everything is dark until you add light. Photographers, whether still or motion picture, worry about light a lot because it makes such a difference to the picture(s) they are taking. With CGI making a pixel light or dark is just a number. Making light look like the real world is hard. It's easy to create a 3D image. It's hard to make the software light it well. Getting surface texture right is part of it, because part of the way you perceive texture is because the way light falls on parts of the surface that are only small distances apart. Toy Story worked well because the characters were mostly plastic toys which have a very predictable texture. Since the first film there have been a few films based on computer games, but they haven't been brilliant because of the uncanny valley effect. Despite the abundance of CGI cartoons are still popular, probably because they aren't realistic. However when I watch Storkhawks I can see how they've used partly CG rendering whilst keeping the stylised cartoon look.
I remember the first time I played a real pinball game after spending a lot of time playing the pinball game that came with Windows NT. I was struck how unpredictable it was. In the NT pinball you could pretty much predict where the ball would go if you flipped it a certain point, whereas the real life one the balls were a lot more random. Perfection in the artificial world is easy, making it realistically imperfect it hard. In the real world, perfection is hard.