The Ecological Trade-Offs of God's Creation

I'm just not an expert at world making. I mean, obviously it seems logically possible that natural history could have been conducted by God so as to prevent the rise of viruses. But then you think about it. Couldn't He have created a world in which God lets us insult each other but prevents us from murdering each other? Think about our legal system. It leaves us free to insult but not free to kill.