I'm sure the very recent change in colors was due people complaining that the arena looked too dark.
Now, the recent colors look very bad, if I may be honest, but it does look bright.
So that got me thinking - obviously, it isn't any more brighter than it used to be. The sky color, is actually darker in blue both for ColorSky and ColorFog(Day).
It seems that a more distinct contrast between the dark landscape(I really suggest the land tile/texture should be changed into something much more bright, lush green..) and the darker blue sky, seems to give people the illusion that the day is actually brighter.
So, here's my suggestion for a 3rd color scheme which is a compromise between the original I've suggested, and so far used, and the very recent one:
ColorCloud[Day] = 170, 170, 170 (00AAAAAA)
ColorCloud[Dusk] = 170, 170, 170 (00AAAAAA)
ColorCloud[Night] = 20, 20, 20 (00141414)
ColorDuskFog[Day] = 255, 149, 88 (3F5895FF)
ColorDuskFog[Dusk] = 255, 138, 36 (3F248AFF)
ColorDuskFog[Night] = 0, 0, 0 (00000000)
ColorFog[Day] = 181, 212, 255 (3FFFD4B5)
ColorFog[Dusk] = 131, 142, 187 (3FBB8E83)
ColorFog[Night] = 21, 20, 16 (3F101415)
ColorLight[Day] = 255, 255, 255 (3FFFFFFF)
ColorLight[Dusk] = 249, 202, 142 (3F8ECAF9)
ColorLight[Night] = 181, 180, 173 (3FADB4B5)
ColorSky[Day] = 111, 160, 255 (3FFFA06F)
ColorSky[Dusk] = 111, 123, 196 (3FC47B6F)
ColorSky[Night] = 0, 0, 0 (00000000)
ColorSun[Day] = 250, 255, 245 (3FF5FFFA)
ColorSun[Dusk] = 253, 240, 185 (00B9F0FD)
ColorSun[Night] = 255, 105, 0 (3F0069FF)
...
Only ColorFog[Day] and ColorSky[Day] settings have been modified, and the rest remain the same as the original suggestion. I'm pretty confident that this one will make the arena look brighter, and better in color, at the same time.