Okay, people, the OP is asking a hypothetical - clearly the OP is ignoring any physics or time-travel fiction issues. "Blah blah paradox," or "blah blah impossible" comments are not helpful.
On topic: no. But not for any reasons mentioned.
Everyone talking about the war, remember that there was an Axis - three nations. Japan would have still attacked us, so WW2 would still have happened. It could even be argued that the war with Japan would have caused enough tech advancement so we wouldn't be much behind where we are now.
On the other hand, Hitler was the enemy that brought much of the world together. The horrors of WW2 helped shape the international laws that have made peace possible. The fact that some modern nations don't play by these rules doesn't make them any less important.
Other posters have also had some good reasons (Hitler being a dumbass for one, modern technology being another, modern culture being the third) which I also agree with.