Leaving humans off completely is not ideal, but I can see why. The other races are apparently mostly single-minded to a person on issues. It would a bit hard to figure out what effect decisions would have on the neutralish humans.
I'm just going to make the assumption that races on countries are the most influential political block of the country, and humans tend to cancel each other out somewhat, so that even in human-majority countries, another race can have the most substantial sway on a country's views.
