In fact, it's morally wrong to be a plague. Because of the population dynamics of a plague, if you content yourself to that status, you are condemning to death by lack of resources (probably starvation) to a great portion of the population, the ones who can't get a hold of resources in front of an exponential growth of the resource consumption. Also, by being a plague, you are condemning the whole of your population to periodic crisis and suffering every time you have to move to a new area because the resources are depleted. Finally, there's a chance you will find some other species that will want to take advantage of those resources, and the same we exterminate the plagues off our crops, they might exterminate us. That would be the ultimate evil.
Humans not behaving like a plague is a great way to avoid a lot of suffering to human beings.