For mentioning ID without dismissing it in the same breath, I have become the subject of abuse and my orthodoxy has been questioned, without having written in favour of ID or against evolutionary theory... I have been variously accused of incompetence and dishonesty, called deluded and mooted as being a Stalinist... The substance of my entries was not addressed, regardless of how correct or mistaken they may have been.
Now, I am very strongly opposed to the "Intelligent Design" movement, but it does our side no favours to hurl unwarranted abuse at the authors of even-handed (even if mistaken) commentary.
In fact - like David Velleman - I would not oppose teaching about ID in high school philosophy classes. Students could examine the arguments on either side, and learn about what separates pseudoscience from the real thing. ID has flourished as a political movement, but it lacks intellectual substance. If students were exposed to a balanced academic critique of it, they may be less likely to be suckered in by ID-ist's claims. Like I said before, getting out the truth has both partisan and non-partisan benefits.
But of course ID has no place in biology classes. The role of high school science classes is to teach the basics of mainstream science. For biology, that means evolution. Critiquing evolution is neither mainstream nor basic. Thus, to teach it anyway would be to both (1) dismiss the experts; and (2) fail to provide students with adequate foundational knowledge. As Michael Sprague writes:
Even if they were right, (which I remind you they are not), it would be inappropriate to teach these "problems" and "alternatives" in high schools. First, even if there were dissent, (which I remind you there's not), no one is denying that an overwhelming majority of biologists strongly endorse evolution, nor, in fact, is anyone in ID denying that organisms do evolve by natural selection. Suppose they were right that neo-Darwinism can't account for some traits. It still accounts for the vast majority of traits; it still explains homology and biogeography and many curious facts of anatomy and physiology; it is still strongly confirmed by a huge body of evidence.
So, rather than "Why not teach the 'problems' and 'alternatives'?" I think the question we should be asking is, "Until ID is also confirmed by a huge body of evidence, why teach it?"
Here's the analogy I have in mind: High school physics, if it even gets to relativity, doesn't address the fact that there are serious problems for the theory (and now we're talking about real problems, unlike when ID people talk about evolution). General relativity is not compatible with quantum mechanics in some cases, though both are very highly confirmed. Thus, physicists have been searching for a way to unify these theories for decades - so far, to my limited knowledge, with little success. Would we think that high-school physics teachers should start speculating about string theory? I suggest that this would be absurd. And string theory isn't even a wedge for creationism!
As a general principle, before you can effectively criticize a theory, you must first learn what the theory is. ID proponents frequently engage in behaviors which suggest that they do not believe this; therefore it is perhaps not surprising that they would argue in favor of teaching kids how to attack evolution before teaching them how it got to be so widely accepted in the first place.