That is silly.
Why do you say that God shows interest? Because He sent the Bible? Oh, please.
God created malaria, guinea worms and all manner of hideous diseases. At least I know that men did not invent them, and who is left?
God shows interest in your mind because that is where your God lives. He could be Zeus, Ahura Mazda or Lord Krishna, and probably would be had you been raised elsewhere..
We use what parts of the Universe we can, it is no more a waste than the air is a waste because we cannot breathe it all, or the sea is a waste because we cannot drink it.
We do what we can. Jesus maybe cured a dozen lepers in the Bible. There were apparently lepers all over the place.
I ask you, when was the last time you saw a leper? I have seen them only in the movies,
Jesus and God did not end leprosy. Humans did it through methodical study of the causes of the disease and figured out a cure. You have to go to really backward parts of the Third World to find a leper.