There’s more complications to classified information that most people understand. One of the biggest parts is the “need to know” part that those without clearances don’t really have a good grasp of how they work. Basically, just because you have a clearance doesn’t mean you have a need to know and get to find out something that is cleared at that level, and that is as much a part of protecting classified information as there clearance level.
In this way, many large projects are worked on by a lot of people where they only know certain parts of it and thus, if just one person gets compromised, that information itself will hopefully result in a more easily contained security breech. In that way, there sometimes are leaks where the information leaked doesn’t seem all that damaging, but in the context of other information that either wasn’t leaked or may have been determined by our enemies, it might be more damaging that it would appear to someone without that context. So generally when people say “oh, that didn’t seem so bad” it doesn’t necessarily mean that it isn’t.
Now, as for what should be classified, that’s difficult to judge. Certainly, even if we believe a well information citizenry is essential to an effective democracy (and I do), I think most reasonable people will agree that information like active military, espionage, and known terrorist information needs to be classified. But there’s other parts of the government that have different reasons for classifying certain information, and a lot of it gets fuzzier and more difficult what should and shouldn’t be. Certainly, there are cases where high ranking officials will classify information simply because it’d be embarassing if the public found out and, IMO, that isn’t the proper use of classification.
But that’s the whole problem here, maybe something I know looks like it’s classified because some Admiral or congressman would be embarrassed if it were public, but I don’t have need to know the full context, so it’s quite possible that there’s something else that I don’t know that could make it damaging to national security and unilaterally releasing that information is a bad idea. For example, let’s imagine say someone finds out about an embarrassing case, like mentioned in the OP, of soldiers killing civilians. Yes, that’s embarrassing, but it’s also possible that it’s classified because they’re still investigating it and it getting released to the public could harm their investigation. It’s also possible that, it contains other important tactical information like spec information on military technology or deployment locations. So someone who leaks that could think they’re being heroic by releasing that embarrassing information, but they’ve also compromised the investigation and possibly prevented those people from being brought to trial; or worse, they compromise a military strategic location and cost the lives of other soldiers who had nothing to do with it.
There’s also the issue that once things are classified, they stay classified and aren’t declassified automatically. So, using the same example, let’s say that there’s a case of a soldier killing civilians, it’s classified because it’s related to military operations and it’s being investigated. There’s no automatic process that says it’s supposed to be automatically declassified when that case is over, someone has to submit it for review. And just because it was important for convicting that one person doesn’t mean that it should be unclassified.
So, yeah, I do think that we need some public discourse about the nature of classification and perhaps there are some things that are being classified for stupid reasons and should be made public, even if it is embarassing to the US. In fact, it would be great to see congress look at updating a lot of laws to consider the greater scope of interest the public has today over even 10-15 years ago in keeping tabs on the government. I’d love to see us look at finding a way to review information periodically that is only classified because no one has done the paperwork to get it declassified. I’d love to see us consider changing what stuff can and can’t be classified and look at loosening some restrictions while maybe tightening others. I’d also love to see some penalties for people who classify stuff that doesn’t necessitate it because, if it isn’t dangerous, the public should know and it only reduces our security and increases cost to have it classified unnecessarily. But we’re not there yet.
Still, I think it’s extremely foolish and dangerous to unilaterally release classified information. By all means, if someone thinks something needs to be released and it’s being blocked, there are ways to escalate those issues without just leaking them. Maybe if it’s one specific document, or a small number, one might have a reasonably strong conviction that they’re just releasing embarrassing infromation, but as far as I know, these leaks are often of thousands of different documents. I don’t think anyone can have that degree of certainty that the information in that many documents doesn’t also include important information that could cause great harm to national security.
So really, in most cases, the people who have access to classified information are quite likely to not have enough context to accurately judge how damaging certain classified information can be. By the very nature of the information, they have to be made higher up by the people who have more context, and those aren’t the sort of people releasing this sort of information. So yeah, that makes those who have been giving these leaks at the very best reckless, and quite likely put the lives of others at risk. And to do so, they not only broke an oath, but they did so knowing that it could carry risk even if they don’t see it themselves. I’m not sure if that necessarily makes them traitors, I don’t know much about the specifics of the information they release or their motivations to feel comfortable making a judgment either way about that, but they definitely should be prosecuted.