I thought that - contrary to the appearances - the black/white symbolism is not racist. I believe it has nothing to do with an unfortunate period in history when people with a very light skin tone were oppressing people with a very dark skin tone. Instead, I suppose, this symbolism stems from the simple fact that humans are diurnal rather than nocturnal. For this reason for centuries, darkness meant one could not see anything. It was much harder to spot an impending danger. It was the brigands' favorite time to pillage our village and woe to you if you overstayed in the forest. From it stems the natural, cross-cultural phenomenon of people using 'dark' and 'black' as a synonym of 'bad,' 'evil,' or 'dangerous,' while 'light' is a synonym of 'good.' It also seems that our bodies need light for biological reasons and lack of light can lead to depression. This, once again, seem to hint that the black/white symbolism has much deeper roots than relationships between people of European and African descend and is orthogonal to the issues of racism.
However, at least in some cases, such usage of these words is frowned upon and declared rasist.
Should we avoid the use of black/white symbolism in our writing, even though color coding things can make the message very clear?
Does unfortunate historical context mean that we should not use the word 'black' for anything with negative connotations and the word 'white' for anything with positive implications? Even though it seems unavoidable anyway because I'd guess that human bodies are biologically predisposed to associate black with grimness and white with joy?