The Consequences Of Vonnegut's Time Travel

In Vonnegut's Slaughterhouse-Five, Billy's time traveling is his experiencing what all Tralfamadorians experience. The aliens experience all of existence at any given time. Thus, they see their existence as a whole. They see consequences and repercussions of their actions at the time they act.
That's the point of Billy's time travel. Humans don't see the whole picture. Humans don't see the consequences and repercussions of their actions. The implication is that, if humans could see, or would think about, the whole picture, they wouldn't do things like bomb the city of Dresden, treat each other cruelly, etc.
Vonnegut uses the Tralfamadorian view of their lives, and Billy's time travelling, to demonstrate this point. Vonnegut was an atheist,
but he was not a nihilist. He satirizes humans with the hope that they will learn to behave better.
At the same time, I would be amiss if I didn't point out another side of the issue. Since neither the Tralfamadorians or Billy can change the future even though they see it, being "unstuck" in time suggests a lack of free will. Billy sees his death before it occurs, but is unable to or at least does not stop it. And the aliens know that they will cause the destruction of the universe, but will do it anyway.