So I thought of another thing... Yet again a warrior stands as comparison because warriors and DK's both have something like stances. Different "modes" in which the class works differently. Now let's look at that. To a warrior, a stance change comes with a major penalty. Not only does it cost alot of rage, it also impacts on what skills you are able to use. But how does it work for DK's? First of all, does it come with a rage penalty, or in their case, a rune penalty? No (at least I don't think so, right?). They can freely switch between stances without any problems. Secondly, are there some skills they can only use in some stances, or in their case, auras? No, they can freely use any skill they want in any aura they want. Great times.
Differences like these is what makes DK's so much better than other classes. Little things that are actually huge things.