I have no idea what you have flown and also have no idea how other jets act since the only jet I've flown is the 145. The 145 reverse makes a HUGE difference. You can even just pop the buckets and keep it at idle reverse and it will stop the plane. If this was a hydroplane incident then the reverse thrust would have got the plane below hydroplane speed faster and the brakes would have had more runway in order to try to get the plane stopped. They more than likely would've stopped on the runway if they had reverse as an option. If they did still manage to go off the end they would've been going slower and maybe not have gotten hurt. While having reverse may not have prevented them from going off the end it more than likely would've prevented the injuries.