Why do atheists speak condescendingly of the negative aspects of an "Intelligent Design".?

I think unnecessary sarcasm is prevalent on both sides. That aside its a bit inconsistent to argue that human perfection or how wonderfully made we are speaks to your deity's existence but then turn around and just allege that the many problems that can be cited are explained away by our fallen nature. You have no evidence for either claim. Its story telling without requiring backing evidence at all.