When I got my Willys (55 cj3b) it had a "roll-bar" made from 2.5" pipe and bolted to the fender wells. Absolutely no roll over protection and since I wanted it more stock looking, I removed it. My thought on a "sport-bar" on any older Jeep is that it is attached to thin, rusted sheetmetal and is probably providing at most a false sense of security.
My Willys doesnt have seat belts either. When I drive it, I drive w/ the same mindset as if I were riding a motorcycle. I also dont drive it over 40 or drive it on busy, fast roads. Mostly through town on neighborhood roads and back country roads. I avoid as much traffic as I can.
If you are planning on using your Jeep in this manner, I see no problem w/ getting rid of the "sport-bar". You cant eliminate seat belts though, and I wouldnt want to be attached to a rolling jeep w/ no other protection. But, thats your call.
If you plan on commuting regularly in traffic, driving at higher speeds or offroading, keep it, and even modify and reinforce it.