Eh i dont see it as that big of a deal. But then again i did not watch star wars movies till 2000's and they were dvd not original.
After watching Episodes I, II and III, you can clearly see that Anakin hates loosing family and friends. Anakin Yelled "Nooooo" in Episode 3 because he was told that Padme died. He loved he so much.
Now, for the part where Vader yells "No, Nooo" in Episode 6, its because hes not going to let his son die, at the hands of the Emperor, who indirectly killed Padme. I find this "No, noo" completely accurate.
No need for "No, noo" if there were no prequels.
So yes it makes sense to add it but just to fit the prequels.
That Noo scene from 3 killed the move to me. It is dead. Between that and the horror of 1... There were only 4-6. NO other movies... The first remakes of 4-6 were not all that bad though.