Sure, a new rear bumper changes the way your Jeep looks, but it does way more than that! It can also allow you to carry an oversized spare tire without worrying about damaging your tailgate hinges. It can also add a rear hitch to your Jeep allowing your to tow a trailer, if it's properly rated of course, or install a bike rack or cargo basket.
A new rear bumper can also make your Jeep more capable off road. Choose a rear bumper with better clearance than the stock bumper for improved departure angles. And most rear bumpers have heavy duty recovery points built in for safer attachments of recovery straps.