The Color Yellow causes Eye Fatigue. Excessive use of yellow can lead to eye-strain. Additionally, it's attention getting aspect is typically used for warning signs that ask quick reaction, like Yield, the Yellow Light, and of course, Police tape. The color yellow can also harness feelings of frustration - people are more likely to lose their temper, and babies subject to rooms painted yellow cry more frequently.
The color red invokes intensity of feeling. It is linked with deep passion not just in love (Hearts, Romance, Roses) but in war as well (Blood). It creates feelings of excitement, and leads to more intense actions amongst humans.
So, Irritability + Frustration + Intensity =

Meanwhile, blue is the color of calmness and serenity. It also harbors sadness, rather than anger. People surrounded by blue tend to be slightly more productive. It is related to aloofness. Hilariously enough, it can also reduce the pulse rate, which in turn reduces body temperature.
White on the other hand creates a sense of space, and creates a sterile image in the watcher's mind. Typically representing purity and innocence. If too much white is used, it creates a cold, empty space.
Really, the color switch was very jarring for people, and it had a deep psychological impact. I'd almost go so far as to say that it's really no one's fault that this happened in particular. No one was aware in a timely enough manor that we practically set up CPMC regulars to suddenly switch gears as if someone pulled a full moon out of the sky and forced everyone to go hakutaku. I remember one of my thoughts when browsing the new theme was that the forum somehow looked a lot smaller than it should be, which I think is related to how I was use to CPMC being white.
If we do end up making another theme change, I'd like to offer a Green with mild dashes of pink, except that would probably get me kicked out of here for trying to murder Letty :V
Also, all hail
free stuff. Communism.