Stopped using them years ago & keep on telling divers around me not to use them. I often feel like don quichotte in doing so though...
The current is often the official reason why people use them around my turf. Then again if your hands can't take the beating, neither can the coral.
As for pointing things out, i've got 10 non-ding ding rods, ie my fingers. The 5 extra centimeters of the ding-ding won't help, if people don't want to look.
Likewise, if pointing with my fingers for 1 minute does not get divers looking, then they must be more happy looking elsewhere and enjoying the ride. Being a Divemaster gives me no right to force them out of their thing.
Lastly, using the rod to stabilise yourself, turn around or move backwards shows a lack of dive skills. Buoyancy, helicopter turns or reverse finning can achieve the same results without upsetting the surroundings. And for photographers who think this does not apply to them: I do not use a ding ding when doing super-macro with a subsee +10 diopter and a 100mm lens.
Ding-dings are worthless dongs...