Tomcat The visual effects of the atmosphere from a design standpoint have to be justified.
The point wasn't to suggest the exact mood but to illustrate that you can drive the mood substantially away from the boring default in various directions using only 4 key technical parameters (lambert+ambient, cast shadows, ao, depth fog)
Tomcat What is the justification for purple fog on a clear sunny afternoon?
Mystery and a warm mood. Also a color temperature contrast between near and distant objects. Btw it wasn't purple but very light pinkish orange 😉
More rationally speaking, in the late afternoon (aka "the magical hour"), the sky can have all kinds of warm hues near the horizon. The distance fog caused by atmospheric scattering will take on those hues as well.
Games use this a lot. Just one quick example:

In general, you should never interpret colors literally and in isolation (grass is green, sky is blue...). This is an extremely naive and crude way of experiencing color. It's the engineer's way, not the artist's way. It will result precisely in that "default" 3d look you ended up with. To generate interest and mood, you can vary or exaggerate hues in all kinds of expressive or unexpected ways. You won't compromise the suspension of disbelief as long as your basic lambertian illumination and cast shadows are kept correct in terms of tonal values, and they always are with computer rendering.