In the episode Back There, a dude went back to the night of Lincoln's assassination and tried to stop it but failed; but in the 80's reboot of the show, someone went back in time before Kennedy's assassination and succeeded. Something about this doesn't seem quite fair.

It was the difference in the tone of the shows. The original show dealt with postwar disillusionment and nihilism. The 80s version was much more futuristic, campy, and fluffy. I don't think politics entered into it.

Even though the show usually only shows or showed things that are possible in the sci-fi/fantasy universe, there was one episode that they could make in reality if two people were anxious to make enemies. It's the episode where this one dude who had joined some lodge was a chatterbox and this other one bet him $500,000 that he couldn't go without talking for a year. Technically, the chatterbox won; and the other one couldn't pay the debt; and the chatterbox couldn't have said something anyway because he had his vocal cords surgically removed. In reality, I'm sure the actor could talk; but it would still be possible.
Take care and God bless

In the episode Back There, a dude went back to the night of Lincoln's assassination and tried to stop it but failed; but in the 80's reboot of the show, someone went back in time before Kennedy's assassination and succeeded. Something about this doesn't seem quite fair.

In the 80s version though, the man who succeeded in stopping JFK's assassination (a descendant with the last name Fitzgerald) made such a mess of the time continuum that he had to sacrifice himself and switch places with JFK, who lived on in his place in the future.