The only problem with that equation is that we often have to make a judgement call without sufficient information. Look at the DDT issue. It's pretty well accepted that millions have died because of the resurgence of malaria. What we don't know is if that's a larger or smaller number than if we continued using DDT. Most think the costs were outweighed by the benefits. But the short term view would have beem keep using the DDT.
And TYWD, this is a perfect example of man trying to do the right thing. It just doesn't get enough play because it's old news and 'global warming' is this decade's "buzz."