How does one decide that a crew error could never be made by another crew in similar circumstances? To me it's a dangerous precedent to make the assumption that no one else could ever make the same mistake. I'd much rather see an investigation that looks for elements of the system that allowed the error to occur in the first place. And corrections need not always be major SOP changes or technical improvements. Sometimes raising awareness through training can be quite effective.
That's part of the challenge. People have to step back, and see if the error is encouraged by the system or if it's an anomalous error by the individual. There's also a grey area, where it's a combination of the two, where the system needs to be tweaked and the individual trained. Using William Edwards Deming's quality principles would be a good idea.