Isn't it God's fault for letting sin have power?

Think about it. God makes all of us able to feel bad and good. That's how our brain is programmed to respond. Why doesn't God make us so that evil can never do bad because no one would feel bad because of it? If he made us so our brain wont respond to bad in a negative way then bad would be powerless! He could just make our minds only feel happiness and then there would be no need to behave because even misbehaving can't hurt anyone because we don't respond to it in a bad way. If God made us so pain wont be able to hurt us because our minds can't feel it then everything would be perfect and the bad would not be able to ever do anything. EVERYTHING and ANYTHING we feel is because our mind is programmed to respond in that way so why doesn't God just make it so it doesn't give us a bad feeling? If he would just do that evil would never be able to be able to harm anyone and we could always be happy no matter what, so why doesn't he?