I think the use of an iron sight is an art form.
There is a place near Ghettysburg PA called "Devil's Den", where the Confederate snipers were able to take out Union officers from as much as 600 yards using iron sights.
Just a stones throw from Devil's Den, there's a river that eyewitnesses say ran red with blood. The rumor for years among the common soldiers was that so many Union soldiers were sniped that the blood ran down into the water. The truth, though, was the blood loss created enormous thirst. Bleeding officers would make their way down to the river, desperate for a drink of water.
I've visited the area many times, and it is so peaceful now. On a cool September day one could stroll through there and never know the blood of patriots that stained the very ground just a short few decades ago. I imagine that isn't too different from other battlefields.
The iron sight has been getting the job done for so long, I doubt it will be replaced any time soon.