It is because God gave mankind free will. So in your specific example the Pharaoh had a choice. How intelligent are we humans compared to ants? Now how intelligent is God compared to humans? There is a reason it is called FAITH, and not FACT, so it would be impossible for anyone to prove or disprove Gods existence. To think that we fully understand Gods will would be more absurd than expecting an ant to know our thoughts. However, it is known to Christians that God obviously loves us because of what he did for us.
On a side note, I would also say another observation is what types of people and families would you want to be a part of. Those that follow the teachings of the Bible or those that don't? Which side seems happier and more content with life?
Now for those that don't believe in any form of Religion, where exactly does your morals come from? I don't ask this to be a cynical, I am just curious. I mean if you could kill a person and society didn't care, but rewarded it for you, would it be ok? If not why?