Regarding the wrap around effect of the black molding, I can see the aluminum stripe which is on top of the molding as providing this effect. As to the black molding itself, perhaps it is intended to give the impression that the Reatta sits low to the ground and provides a sleeker profile..............
I think it does that to. Don't know if GM intentionally did it for that reason. I think the pinstripe does the same thing. I removed the pinstripe on mine and I think it makes it look a little fatter. Gives it more of a '68 Camaro look.
The strut on the Reatta not only acts as a damper it is an integral part of the suspension. It holds the knuckle so the camber is in correct alignment as the knuckle goes up and down. The knuckle pivots on one bolt in the lower control arm. Without a strut to keep the knuckle aligned vertically, it will just flop over as can be seen in the photo below. The blocks of wood you see are to keep the knuckle from flopping over and putting a strain on the ABS sensors. Because of the side load on the strut, the rod is a larger diameter than a shock.