I share similar thought processes in some ways. When I see something in a primary document that does not align with my preconceptions, I like to sit back and ask why it does not fit, and how I could make it fit ... or what do I need to change in my preconceptions.
I recognize the morale impact of receiving such fire, especially for the first time. And I agree with you that why a should begin to fire early could easily be due to weakening morale in the unit awaiting attack.
60 casualties for 36,000 shots is 1 in 6,000. One can argue what the ratio is today, and it depends on how you count. It is true that the overwhelming majority of shots do cause a casualty. The principle reason is that most fire is not actually expected to hit anything. It is intended to deny ground to the enemy. If a volume of space is sufficiently dangerous, it is hard to move troops into and through it. The second reason (at least for infantry) is that only a proportion of people actually aim at an enemy. There is a primal understanding that "if I can see him to shoot at him, then he can see me to shoot back". And, there are also a lot of misses. Hitting a target, especially in the field, is harder than most people realize.
I would infer that you agree that my probabilities of hit in my previous responses were very generous :) If so, you would follow my logic that the actual number of hits would be very, very low at extreme range. But ... that does NOT diminish the morale implications which you raise. This was why I said in my first response that I feel both you and Digby are correct. The material effect of such fire is negligible, the morale effect may not be.