May just be the case of a bad luck or not fidgeting enough with trying to find a colorscheme to one's taste. I have several colorschemes - not ideal, but decent enough to love and use - that I switch between depending on room lightning and language.

Book comparison is far-fetched imo. Code is not just a regular text, it's a very structured text, and reader of a structured text benefits from structure hints (expressed via color and identification), while writer of such a text benefits even more from on-the-go error checking. Looking through a dictionary without any bolds, italics and structure, just paragraphs and paragraphs of text, would be a waste of time and a pain to the eyes. And this is what I tend to do about 95% of time when 'writing' code - looking at it.

I would recommend searching for a less contrast or vibrant colorschemes like popular Solarized (too low contrast for me actually) or Tomorrow themes.