If the average life in the universe turns out to be absolutely miserable, is it a good thing if I bring a child into existence that will have a life that goes slightly less miserable? Or similarly, if the average life is free of suffering and full of the most intense happiness possible, would I be acting catastrophically wrong if I brought into existence a lot of beings that constantly experience the peak of current human happiness (without ever having preferences unfulfilled too), simply because it would lower the overall average?

More repugnant than that is that naive average utilitarianism would seem to say that killing the least happy person in the world is a good thing, no matter how happy they are.