Certified GKH Gardening Expert
Let's start with looking at the plant as a whole. It's shape is an indication that it has developed a taller stature to harvest light above its competition. The thickness of the leaves suggest that it is semi drought tolerant, and will not lose as much moisture through them.
This thick leaf is also less appealing to creatures that may want to eat them.
Another advantage to a thick leaf will be tolerance to a broader range of climate conditions, such as cold or heat.
This article will give you more information on the shrub.