Seemed there was a lack of interest in this thread so I was willing to let it die, but, since you ask, Mav, the intended answer was that the public furor about each left out an important aspect of the original. In the case of the "Great Eskimo Snow Hoax" a brief history might be in order. The first stating of the Eskimo Snow Question had the number of words set at about four. This number started to blossom almost immediately getting up to at least 100 in some versions, but the important aspect that got lost very quickly was the contention that the Eskimos had no word that covered all aspects of what we know as snow. In the case of Ebonics the hoohah was all about worries that teachers were going to be teaching children substandard English. As one of the teachers in the PBS special Do You Speak American? said, "We don't have to teach them Ebonics; they already know all the grammar rules of Ebonics." The reason for bringing up the fact that they have a dialect with rules all its own was to be able to show how one could translate from AAL (African-American Language) to SWE (Standard Written [but it might as well be White] English).

As for pointing out differences being a "way of reinforcing difference/applying value judgments rather than finding commonality," I think that ignoring differences that are obviously there is more likely to act as a way of applying value judgements. If you are told that the way you speak is simply wrong you will feel more judged than if you discover that the way you speak does have rules but if you want a good-paying job you'd do better speaking with a different set of rules.