Spinoza believed that "good" and "bad" were adjectives without any reality to them. He was a determinist who believed that everything was God, or Nature, and thus everything just is. How can we avoid that conclusion if we believe that God has ordained all events, all happenings?
From the transcendent viewpoint, all things are ordained by God and occur because he choose that they would. He ordained these things in order that he might be glorified, and thus does not sin in doing them. So can we say that anything that happens ought not to have happened? No, not from here.
From the immanent viewpoint, on the other hand, we can say that events ought not to have happened. When we look from the immanent perspective we are not considering that world in all of time and space, and God's ordaining deterministically occurs with a consideration of the whole of time and space. When we view things immanently, we are not considering the future and thus are not considering that when Christ shall return and redeem all things. At that time, which we look forward to, what occurred which was evil in its time shall be taken and untwisted by our Lord and Savior as he redeems the whole of creation. But until then, we can say that it was twisted, and it is twisted that certain things happen. Sin in the world takes the good and twists it into evil, but Christ shall take evil and untwist it into even greater good, because it will be good not only because God made it so, but also because, when it ceased to be good, God took it and did not throw it away, but made it good again. Yet, until that time, there are evils which ought not be, and to add to the evils is to take what God has made and tamper with his creation. It is meddling in the work of God, a claim that we can somehow make the world better than God could alone. We do not act with knowledge and ordination over all of time and space, so we should not act like we do, but like we serve the one who does.
Well, if we should not tamper with what God has made, should we just do nothing? No, even before the fall humans were instructed to tend the garden, be fruitful, and multiply. Now that the world has fallen, and the earth is twisted from how it was in the beginning, we ought to desire to make it as it was originally made to be, glorifying God in every way it can, just as God will finally and fully do when Christ returns.
Thus, destruction of life is an evil because God did not create the world in such a state that it should contain that, and when Christ returns we shall no longer suffer from it. In this time, we encounter it, and fight it, knowing that when it happens God has ordained it for good, but that we are to seek to put creation right, that is, more like the state it will be put in when Christ returns, for the same reason that we are to do good works: it is an overflow of our hearts toward God in worship, that we desire the world to show his glory to all people.