Because the steering box, and steering shaft are not 100 percent lined up. The angle of the shaft VS the angle of the steering box, are not the same. There needs to be flex to compensate for this. I think its 94 back, that can be swapped with A C J Jeep U joint but this is not an option on maybe 95 up because of the 3 steering shafts. This will allow the U joint to miss align with the steering shafts and cause all kind if problems. Dont quote me on all of this, but I think thats how it is. I do know that this is the reason for the rag joint though. A new rag joint will make a world of difference. I replaced mine a few years ago. I have almost no play in my steering wheel. My steering is tight as it should be. Also with the 275/60/15s all the way around, my truck is very responsive.