In order to make sense of the headline, there are two things that one needs to do.
Read this piece about Darwin. And, before you start objecting, "This couldn't have been done in six [earth] days!" I agree completely and so does every other scientist. For the second part, go here and scroll down to Six Days of Genesis.
Finally, to answer the question, "Why did the "designer" do such a lousy job?" I'd argue the opposite that the laws of science (gravity, physics, etc.) are magnificent and miraculous. As to why humans get diseases, etc., there is the same explanation we've had for six thousand years: original sin.
Again, read the red and blue links and make up your own mind.