We could talk/write for hours about adjustable sway bar links. The easy "answer" or fact of the matter is that if you're lowered, you likely need adjustable links.
Sway bars act as another "spring" on any vehicle. They simply attach the left and right suspension (whether front or rear) together. When the vehicle turns, it loads one side of the suspension while trying to lift the opposite side. The sway bar is what prevents this from happening. What you don't want is "preload" on your sway bar causing additional "spring rate". Again, we could go on for hours about suspension tuning, corner balancing, proper alignments, etc, but there just isn't enough "ink".