Quite simply, the map voting ENSURES server traffic. Whereas not having will, in my opinion, highly alter the amount of traffic you have due to MANY people hating GOOD maps, such as cbble, vertigo(not great, but good), the cpl maps, prodigy, and probably a few others. I say keep the voting, change it to nominations, then you can change how often a map is allowed to be played also. I think this would be the best option.
Edit: If this were to be chosen, I think it should be at least 4 OTHER maps before this one can be played again.