From Diablo Wiki
Remove greens and blues
d2 was saturated
http://multiplayerblog.mtv.com/2008/07/31/diablo-iii-designer-talks-colors/ "We're very happy with how the art style is. The art team's happy. The company's happy. We really like this art style, and we're not changing it."
But fans take note: The decision to add color to the macabre world of 'Diablo' didn't come lightly. "It's actually the thing we struggled with the most," Wilson said. When Wilson joined the project two and-a-half years ago, the game was similar-looking to what fans of the old games might expect - darker, desaturated and a lot of brown and gray tones. However, translating the game from 2D to 3D with a dark color palette didn't make for the best gameplay experience. The first and second iterations of the art direction had a "modern, gritty look" but made it difficult to distinguish enemies from the environment. "When you have 30 creatures on screen - and four or five different types - target prioritization is a factor," he said. "You need to be able to tell those things apart fast, and you can't do that when your world is gray and your creatures are gray."
The first and second iterations of the art direction had a “modern, gritty look” but made it difficult to distinguish enemies from the environment.
We didn’t want you to look at ‘Diablo III’ and go, ‘Oh, that looks like ‘Gears of War.'
RyTEK http://forums.diii.net/member.php?u=321929 Jay is saying that 3D models reflect ambient light, therefore the background must emit light. This happens particularly through phong shading-esque techniques.
SSH83... here is something to think about: colorful monsters go a long way in making a game look extremely fake. To explain, if an environment is colored properly, the monsters will be visible because of light emitting from torches, windows, spells that are cast, sunlight, etc. This AMBIENT light bounces off of them and then is visible in the world. If the environment is gray but monsters are blue or green or red, then the monsters seem to be emanating color from some unknown light source (their skin?)
I'm not trying to argue that this should be a photo realistic game, but monsters "lighting themselves" will go a long way to look like sprites pasted on a stationary background. This, I think, is the problem that Jay Wilson is saying happens with 3D models.