It turns out the color scheme wasn't standardized until after the 2000 election. So it could be by accident or it could be that was the color association that subconsciously resonated. The article notes that in many foreign countries, red is used to denote communist/socialist/left-wing parties and countries (USSR and China quite notably) while blue is associated with right-wing parties. Has the Republican party really forgot that they used to use "red" as a smear?
Cartophiliacs are of course aware that two colors are insufficient for distinguishing a map. You need four colors to be sure one state doesn't become indistinguishable with the next.