[yossarian19]

4 links use coil springs or, better yet, coil overs. These will handle more like a car and offer more / easier adjustment than leaf springs though at the cost of some stability. Enter the rear sway bar, you've got a much faster / smoother handling truck that doesn't like to carry freight as well.
A 4 link also resists axle wrap, where under acceleration the pinion will want to rise and twist the springs up. A traction bar (a single link) can be added to a leaf suspension to limit axle wrap, too - but you get none of the other benefits of a coil spring rear.
Leaves are still used in many trucks / SUVs for a reason. They are also missing form a lot of SUVs, again, for a reason.