But what on earth is wrong with humans playing God?

This is a quote from Minette Marrin, a news commentator for the Sunday Times in England concerning the use of pre-implantation genetic diagnosis (PGD) commonly used in fertility clinics throughout the world. This process allows the parents to create the usual batch of test tube babies and then genetically test the embryo. These tests are to allow parents to choose what sex of a child they want, even to allow parents to create a child for the purpose of using its umbilical cord blood to help another sibling with a serious illness. PGD is even used to 'eliminate' embryos which have genes scientist think might lead to cancer at some indeterminable time in the future. And who knows what effects this process will have of removing a single cell for this process from an embryo at this young age.
Minette was "dazzled by the inventiveness and compassion" of the PGD process and said "It will be easier and better in every way to get rid of a tiny collection of cells." I have a hard time following this logic (or lack there of). Imagine a couple which is having trouble conceiving goes to a fertility clinic. What they could not do naturally, science does in a lab and a scientist, which the family will never meet, decides which embryo will be chosen to be their child and which will be left to die on the counter.
Where does the madness stop? Now researchers are looking for chances of disseases which could occur in the person's middle ages! One person had the scientist screen the embryos for an arthritis gene which only has a 20% chance of developing! And don't forget cancer, which scientist think a gene is responcible for only 5% of all cases of breast cancer. Let's be carefull of this practice that has developed in Britain, because we don't know where it will end.
For example, there is the lady whose doctor tried to pressure her into having an abortion when in the 35th week of pregnency, her baby was diagnosed with Down syndrome. That is just a week or two from popping out of the oven, and could already live without trouble outside of the womb! But the doctor only talked of the hardships with raising a disabled child, neer once mentioning how many families say a disabled child has finally opened their eyes to what love truely is (and by the way, is it morally right to kill a person because it causes you a percieved inconenience in the future? Try the logic to that out and I could kill anyone I wanted). But, it gets worse than that. 62% of children with Down syndrome are diagnosed in the womb, and sadly, 92% of those children are killed. And it gets worse.
Over 20 babies have been killed in the third trimester because they were diagnosed with club feet in the womb. Four others killed in the third trimester because they were diagnosed with webbed feet or fingers. And 12 others were killed in the third trimester because they were diagnosed with a cleft palate and dwarfism. All of these, except dwarfism, can be cured with basic and fairly common surgery. And the little person! It's a perfectly healthy child, just a little smaller than usual. The devil has to be smiling over all of this. And that is why it is NOT ok for humans to play God, because man is too ignorant to see the consequences of their power. And some people, like Mrs. Marrin, bask in this ignorance.