I agree completely. The addition of a life worth living is exactly that: worth it. But then you have the idea of Average Utilitarianism back. Do you want a bunch of low positive happiness citizens in a population, or a low population with high average utilitarianism? The only issue pointed out is that you can have a population of 1 with slightly higher happiness than a population of 5 million with slightly lower happiness each. So what? In the end, happiness is only important because it's what any individual wants. The whole justification for Utilitarianism is based around the principle that happiness is the end all be all for every individual. That being said, the counter intuitive nature of this complain means nothing, especially since intuition means very little in regards to logic.