The primary purpose of humanity is to survive until we can destroy or genetically alter most of the feeling life on Earth. This is for their own benefit. They are tossed into the Darwinian gladiatorial arena called the natural world without their consent. Only human parents understand the concept of pondering whether or not new life will be created.
Empathy is a logical conclusion all psychologies tend to veer towards, given enough time. Our descendants will handle that problem for us. They will have the empathy to destroy certain species, genetically modify others, or perhaps merely destroy all non-tool-using life forms they find.
We just need to survive long enough for them to do so. The cost of humanity not surviving could be trillions of years of suffering for trillions of organisms, all throughout our galaxy.
It is not only okay for humanity to play God...it is with the utmost urgency that we should do so. We must re-shape this universe in which we live, steal the throne from the blind, mad scientist who rules it named Mother Nature, and re-build it in our image. Mindless evolutionary processes have no intelligence, no empathy, no sense of morals. It is the worst mother we could have asked for...but the descendants of humanity can be the new Gods of the universe, kinder gods, gentler gods, gods who understand right and wrong.