I confess that this particular controversy has always perplexed me. If, for religious reasons, you flatly oppose the creation and destruction of embryos, then I disagree with you but I understand your objection. Outside of that, though, who cares if parents start selecting for left-handed saxophone players with a gift for languages? It's true that as the technology progresses, it will probably become possible to perform more problematic types of screening — perhaps for behavioral traits like sexual orientation or political persuasion — but there's every reason to think that this is a lot harder than it sounds no matter how good the technology gets. And in any case, parents already select for these traits constantly when they make decisions about how and where to raise their children, and nobody objects to that.
In short, what's the big deal? Which is fine at the outset at least, because nobody really thinks it's all that evil for anybody to want their kids to have blue eyes instead of green. The problem of course, is that parents aren't stopping there. Like many, Kevin doesn't seem to realize that parents are already utilizing IVF to select for characteristics that aren't nearly as insignificant as eye color. In fact, some parents have gone so far as to use reproductive technology to create children with disabilities (deafness in one case.) Kevin's dismissive of concerns over kids with pre-selected eye color, but we're already past that point.
The problem with this of course is that our laws haven't kept up. That appears to be largely because people like Kevin Drum (and many others, to be fair) don't seem to realize what doctors utilizing reproductive technologies are already capable of (and doctors are only now realizing what risks these procedures entail.) Now it's entirely true that it's only a tiny minority of parents who would be so brazen as to design a child to be born with a disability, but we don't fail to pass laws against child abuse just because it's a tiny minority of parents who abuse their kids. It's past time for state legislatures to address this possibility, and past time for us to have a real public debate on the matter.