To turn your argument back, it would seem to me that keeping this info under wraps and not make it public would save American lives.
Well...apparently during several of the investigations (or at least the first few months of them) it was kept under tight wraps.
Problem is, these photos were flying all over the place, not just the old-fashioned hand-to-hand network consisting of people giving them to each other in person, but the internet as well. It's out there, it's done, now the mess has to be cleaned up - you can't push something like this under the rug as much as some would like to. The pictures being shown outside of the US are very very bad. The media is giving us the watered down, blurred pics. If you go googling around some of the foreign news services, you'll see what I mean
The best way to clean this up, is to make sure that those who should be punished are punished, and make it just as public as somebody doing the same things here in the US/civilian world.
The spotlight is on us, and just how committed we are to things like the rule of law. If we are telling the Iraqis "your free from the atrocities of the past, you have actual rights, etc.", while the very same people (US military) who we say liberated them are breaking the laws, are doing things that they thought disappeared with the ouster of Saddam, they will have no confidence at all in any system we setup and they will be suspicious of our soldiers.
If they have no faith in us (the US), then they will have no faith in the systems we help setup. At that point the hundreds of soldiers killed, the thousands wounded, the billions we have spent, will be all for naught. Iraq will go right back to the way it was. All those Iraqis who have helped us, some will not do so or be afraid of us, and it could cost even more lives since people might not be so quick to inform on other Iraqis.