I beg to differ, my friend. The Element below seems to have supported itself on the roof perfectly well. Modern vehicles have to pass certain rollover crash-worthiness criteria, unlike older vehicles, and most, if not all vehicles are relatively safe in rollovers.
As to four-point harnesses, a
properly installed set of harnesses are far more safe than a simple three-point system, or the FAA would be having them installed in aircraft to this day! A five-point harness system would be ideal when installed correctly, but given the nature of the vehicle, that'd be overkill, IMHO.
All four point harnesses have detailed instructions that specifically point out the angle at which the harnesses are to be installed, so if they're installed incorrectly, the danger is not the harness/manufacturer's fault, but rather the installer/operator.
Also, I very much doubt that
all harness bars are as dangerous as you say. I could understand if it were merely tack-welded on, but I do know that the NHRA requires fully welded joints, as well as bracing. They even give detailed instructions as to how to properly construct a harness/roll bar with pipe dimensions and material.
Properly constructed, a roll bar or harness bar, along with a
properly installed 4-point harness system
can and does increase your safety in the event of an accident, otherwise they would still be using stock 3-point belts in racing.