Godwin's Law is important because it shows the cost of attaching baggage to your arguments. I think that if you can argue that something is bad by invoking Hitler, you can argue that something is bad without invoking Hitler. It's not just that going Godwin is tacky. It is, or should be, a sign of rhetorical weakness.
I don't think the problem described by Godwin's Law is that bad arguments cheapen Hitler. I think the problem is that Hitler cheapens one's arguments, unless one is arguing about genocide. Sure, you can draw lesser lessons from Hitler's lesser crimes (ie gun control), but the implication, intentional or not, is that the lesser crime you're arguing about is on par with the Holocaust.
While bad arguments can be made with Hitler, good arguments can be made with Hitler as well. These arguments do not necessarily need to use Hitler, but they can. They frequently do because comparisons to Hitler are accessible. Nobody needs to explain who Hitler was; nobody needs to tap out of the conversation for a few minutes to go read the Hitler wikipedia page.
Why not use an example other than Hitler here on HN then? I'd assume people here are reasonably well educated and don't need intellectual spoonfeeding.
I don't think the problem described by Godwin's Law is that bad arguments cheapen Hitler. I think the problem is that Hitler cheapens one's arguments, unless one is arguing about genocide. Sure, you can draw lesser lessons from Hitler's lesser crimes (ie gun control), but the implication, intentional or not, is that the lesser crime you're arguing about is on par with the Holocaust.