Because you unhook the front swaybar to allow the rear tires to always stay planted and you go places that your 4WD friends with no lockers have trouble with. That and driving to a ski area every night at midnight on unplowed roads to groom, 200lbs of gravel tubes in the back and a locker and there's no stopping it.
NWPhotog, you won't want the spacers, they're homemade and they are basically two 1 inch thick poly (thick cuttingboard material) spacers. The rear has the rear half overloads (used to get about 8 whitewater kayaks up on the topper) and the short stubby add-a-leafs.
Yeah, this is my old Comanche, finally picked up a WJ (finally a 4WD) to be able to bring my 2 year old along, child seats don't work so great in an MJ. Was kind of sad when it left on the trailer, lots of great memories in that truck, but it least it went to a good home.
Have fun with it William.