you end up wondering why the hell Sam Beckett wasn't sent back to kill Hitler
If they played that the way Stephen Fry did in Making History, that could have been a riot. (Very short summary: preventing Mrs. Hitler from conceiving made the whole thing worse, as someone subtle, intelligent and Hollywood-worthy took the top spot.)
I saw one Twilight Zone where a woman was sent to kill Hitler as a baby, only it turned out that she killed the wrong baby. She did kill the child of Mr and Mrs Hitler, but then the nanny in charge bought a replacement baby and the parents never knew - which might suggest something about why he ended up evil.
Sounds vaguely like the plot of Good Omens.
There's a bit of similarity - and the idea that there's only so much a human can do to alter what Fate wants. That, or both writers had strong opinions in the nature vs. nurture debate.
One of the premises of Fritz Leiber's Changewar series (which was exactly about two opposing groups that went back in history and fucked with the timeline to eradicate the other) was that forces of history were difficult to divert. Everybody should read
The Big Time
and somebody should make it into a play too.
To Say Nothing of the Dog comes to the same conclusion.
Connie Willis's "Doomsday Book" also seems to have a similar theme.
Well, they are set in the same universe.
I loved Domesday Book, but wished someone had warned me before I started reading it how FUCKING DEPRESSING it was. I had no idea, and couldn't put it down, and was all sniffly, and it was NOT what I needed right then...
I thought the warning was not to read "Doomsday" when ill.