I rolled a Jeep Wrangler, did 3 complete revolutions down a hill and into a field. Standard seatbelt and the rollover bar saved both me and my brothers life or from serious injury.
I completely agree that rollover bars should be accompanied by other safety equipment to function to the highest degree. But my experience is so vivid and makes me subjective on roll bars.
In the Wrangler accident I made impact with the top of my head and both my hands on the ground during the first of the revolutions. The seatbelt held me back but one of my hands came in between the rollbar and the soft soil of the hill. Slightly bruised and knocked about, with broken glass from the windshield in my eyes, yet mostly unharmed. My bodys natural reaction was to "reach up to catch my fall" when the car was upside down, and therefore my hands where placed in the most dangerous place for them to be. Luckily it was soft soil instead of hard asphalt.
The accident happened during winter time on a reasonably straight road with near to clear ice. The reason for the accident was my inexperience in driving a strong 4.0 litre automatic engine packing over 200 hp to the rear wheels and an automatic gearbox on slippery surfaces. (Yes I was young, and had only held a licence for half a year
The police took away my licence for 6 months even though I was driving under the limit, as we have a law stating you need to "drive as the conditions allow."
As for the Wrangler, after the roll all four wheels where broken off, the rear axle was broken, the windshield was obliterated and seriously dinged. The roll bar has moved slightly into the body of the car, and had a 15 cm "V" shaped depression in the middle. All four wheel arches where smashed into the body, the front bumper was offset around 8 cm to the side, and the cars frame was both twisted and bendt.
Now 16 years later I'm a different and more experienced driver, with no accidents for 14 years. So the roll bar is probably unneccesary, but as I stated, subjective on the topic...