Here's an edited version of a puzzle from the book "Chuck Klosterman four" by Chuck Klosterman.
It is 1933. Somehow you find yourself in a position where you can effortlessly steal Adolf Hitler's wallet. The theft will not effect his rise to power, the nature of WW2, or the Holocaust. There is no important identification in the wallet, but the act will cost Hitler forty dollars and completely ruin his evening. You don't need the money. The odds that you will be caught committing the crime are negligible. Do you do it?
When should you punish someone for a crime they will commit in the future? Discuss.
Of course it wouldn't be time travel. People who were especially good at predicting other people's life paths would just do so and punish accordingly, or something.
Edit: I accept your point that future consequences don't suffice to justify time-travelling punishment.