I think there is an additional problem of schools not being challenging enough for most kids, and many available GT offerings are probably beneficial to lots of kids, whether or not they would pass the CogAT without prepping. If a little prepping will lead to an adequate education, where otherwise it might be underwhelming, then in that situation I say go for it.
Also, I imagine if my kid were not a good test taker, I have a feeling I would want to help him out by familiarizing him with the types of things that might be on a test. Since I don't have that issue, and my kid scores super high on every test he's taken, I cannot fault others for their choices.
It would be nice if all the kids were in the same boat with these tests, starting with no prep so you could get a fairly good apples to apples comparison, but in reality it ain't gonna happen.
