Following along the same lines as Mikelink45, the effect of stringing together several hits on the pitcher is more noticeable than a single swing. Both situations may only result in a single run scoring. But with a home run, the pitcher can easily say "just one pitch that got away from me" and recover quickly while a string of base hits will likely cause some serious doubts to entire the fragile mind of a pitcher. Add to that, the threat of a stolen base, a change to the pitcher's preferred use of a full wind up, and pressure on the pitcher to stop the bleeding, and the impact is even greater. And, to me, it's more fun to watch all the thinking going on by both teams when there are players on base.