I agree with pretty much everything you've said in this comment chain, except the part about everything that's currently alive being sustained by the auffering of some other living thing...the very plants we're speaking about get their energy from a combination of sunlight and air (specifically carbon dioxide). AFAIK, we haven't found that soil reacts to having nutrients extracted, and the sunlight and air are there anyway. So, if any organism can look down on us for our cruelty, it'd be the non-carniverous plants ;)