No, because WWII was unavoidable, and Hitler wasn't needed to make it happen. He just brought the hatred out, and managed to take power with his words. If someone less incompetent in military strategy had taken over, and given the war effort to Germany's generals, then we may very well have lost the war. Hitler being in command helped us win, because he had no idea how to run a military campaign.
Also, although some won't admit it, the Holocaust actually accelerated medical science, because the experiments they performed couldn't be done without severe legal backlash. While the things they did were absolutely horrible, they still managed to make some incredible breakthroughs.
Not only that, but life is life. If you were to go back in time and kill Hitler before he could start his Reich, then not much would change. Sure, less people would die, but at the same time the war would have gone on without him, and if someone else was at the wheel, then we would have a good chance of losing.