Point taken about the height difference, and even if the helicopter hit the bridge, I doubt the structural integrity would suffer.(Of the bridge, not the heli.!)
What does suffer is the public perception of helicopters and general aviation as a whole. Where do you draw the line with how high the bridge has to be before it changes from harmless fun to a dangerous act? If the pilot is seen to get away with it how low does the next thrill seeker go?
A controlled exercise for filming with proper recces is one thing, a quick spur of the moment dash is another.