One of the most frustrating things about wars is people adopt policies that don't advance their objectives and then lie about what they're doing, what happened and why. This sets up an environment where militarys do things that aren't even in their own interests, let alone anyone else's, and the public discourse is busy arguing about some wild imaginary scenario that isn't related. Better to have people focused on the real world and accurately understanding both (1) what the policy was and (2) what the outcome of the policy was.
If I admit to killing someone because I want everyone to know I'm a tough, viscous killer and they'd better not piss me off or they'll be next - that's not an improvement.
As to the behavior itself, I imagine the merits are heavily dependent on context. International politics depends to some extent on demonstrating a willingness and ability to engage in violence. That's not the whole story but it's definitely part of it.
Not really, IMO. Their goal isn't honesty and transparency, they just DGAF to hide it because they correctly realize there won't be any personal consequences for their actions.
They are still lying about most everything else - why the war was started, suppressing the amount of causalities, etc.
That's a fair point, the major change isn't that we suddenly started committing war crimes, it is that we've dropped all pretenses of trying to justify why what we did isn't one.