If you raise or lower the car, the swaybar will rotate. If the swaybar is vertical at rest, you can imagine what would happen when you corner - you'd be flexing the bar, not twisting it. It's best to keep it close to horizontal so you use it in torsion only, and have the correct lever arm length.
But, if you dropped your car so low that's a problem, you're way lower than you want to be for optimum handling, and so you probably don't care about a tiny difference in roll stiffness. Also, you don't need adjustable end links for that - just shorter/longer ones.