One thing you should be aware of if you tow over the manufacturer's rated towing weight is that, in the case of an accident, you might be held legally liable even if it wasn't strictly your fault. This point seems to get ignored over and over but it is important. It's not just about whether you have enough power to get it all moving or enough brakes to stop it all or enough stability to keep it under control. Those things are, of course, very important. But in the case of an accident, the law takes over and you could find yourself in a bad place. I'm not an expert on any of this but I did do some research on it before I bought a small tent trailer to tow with my XJ. It is probably prudent to check with your insurance company and the police first just to be sure you aren't putting yourself needlessly at risk.
That is a good point. If you tow over the manufacturer's limit, you do so at your own risk in case of an accident. That said, I can't think of any reason that the JK's tow rating is so low. I believe the Jeep engineers were asked that question a while back during a jeepforum q and a and they didn't give any really satisfactory answer either.
07 Jeep Green Rubi Unlimited, auto
Mods: Tuffy Cubby Storage Cover, Rugged Ridge grab handles, Shrockworks Sliders, Rock Hard Engine / Gas Tank Skids, Rhino-lined tub, Kilby Evap Can Relocation Kit, 16x8 Centerline Wilderness Series - Falcon Rims, 285/75/16 Interco SSRs, OME 2" HD Lift, PSC Diff Covers, Superwinch EPi 9.0, BulldogFab Rear Bumper, RedrockFab Front Bumper and skid