Is conflict ever a good or necessary thing?

I believe that conflict is necessary sometimes, for example, when my sister and I are fighting we need to talk it out, although sometimes it gets a little more violent. Most of the time we work it out, escaping with little or no scratches, our problem resolved. If someone had interfered, our issue would not have been solved, and we would have remained annoyed with each other for a while after that, or as Heidi would say, "for a really loooooong long time."
I do not think however, that conflict on a bigger scale, such as taking issues to the point of war, is necessary. There are better ways to resolve problems. WWII was a different case. If the United States and its allies hadn't fought back against Hitler, we would all be annihilated except for a handful of "perfect people." It was important to take a stand against evil.
In narratives and stories, conflict is definitely a good thing. It keeps the story moving, which keeps the interest of the reader. Characters are usually not completely good or completely bad. They are more complex than that, and have little conflicts within themselves, which makes the story believable.
In competitions and in sports, conflict helps to push people, to motivate them to do better. Some people are very competitive, and do better with conflict and obstacles to overcome.
There are also some conflicts that I would rather not deal with, such as conflict with my hair. Every morning my hair and I fight, as I'm trying to brush out the knots from the night before. I have learned to put my hair up, and I suppose this conflict is a good thing, since I learned from these incidents, though I wish I didn't have to deal with it. And going bald is NOT a solution to this conflict, for all of you out there who have just grabbed a pair of scissors to chop off my hair as a favor to me.
In short, a little conflict never hurt anybody, but too much conflict can hurt everybody.