I make my living building roll cages. One important thing I have to say about driving with a roll cage is, wear a helmet and proper 6 point seat belts to protect yourself from the cage. The Monteros have proven themselves repeatedly to provide us as much protection as available on the street. Adding a cage will both stiffen the bodyshell increasing the G loads during a heavy impact as well as a strong chance for blunt object injury to the head.
Here in America we have very few regulations as far as modifications we do to our vehicles but overseas some countries do not even allow roll cages in road cars unless the vehicle is actively used in competition.

I do drive caged cars on the street and am very aware of both the benefits and danger of adding a cage in a vehicle. I have also seen too many poorly made cages that encroach on the passenger area or front tubes that are not forward of the pedals increasing the chance of foot entrapment in frontal impact. There is no place to scrimp on safety gear and the streets are not the best place for some types of safety gear or devices.

GWs Montero did the best it could to protect his family in a very hard multiple strike impact. A cage would not have helped and more than likely might have caused massive head injuries. He and his fiance survived. She has suffered serious injuries and I expect is a long way from walking the streets. It is sad that they lost their child but they will both be able to get back to life in a case where a rollcage might have been the wrong safety device.