Well, back in the 2000-2006 generation, the Tahoes and Yukons both had the black applique. The Escalade was the only model to have a body matching one. I guess they stuck to that, for whatever reason they decided to make those black in the first place is beyond me.
I would think that it's something in the same reasoning as making the LS body parts black plastic. If you buy an LT/LTZ, you get matching handles. And if you buy an Escalade, you get matching appliques.
And then with the 07+ models, they stuck with black because that's what that's what color the previous appliques were.. And I guess because the black makes the rear windows look longer? That might have something to do with it. Who knows.
But back to the LS handles, that reminds me, I've always wondered why I never see any 07+ Yukons with LS handles. So basically GM is confusing, haha.