An exchange should be able to understand without any voting, and for it's own good, that it needs both drk AND doge for volume.
why not having some voting for this?
it's a good competition

I don't see the point from the perspective of the exchange, unless to self-advertise. What is there to compete? You are an exchange, you want volume so that you can make money on fees. Therefore you add as many high-volume coins as you can and get the money from their trading.