Why? I don't believe this to be true...given a little bit of effort.
I'm not expecting my jeep to be as quiet as a luxury sedan. However, if my effort means that my family will be more likely willing to sit through a long road trip to go wheelin, well that's worth it to me.
I agree that you can indeed improve the Jeep's sound levels with sound control products...I just completed installing Kilmat on the entire tub of my JKUR and it made a noticeable difference in highway road noise. I'm going to be doing the doors next, and will complete it all with a DYI...