I don't know if I'd go so far as to say it shouldn't have happened, because it really solidified the nation (at the expense of the south, but dividing the nation would have ended badly for both sides in the end if it came to that; division would have robbed the United States of its strength [unity and thus control and shared benefit of the natural resources of North America] and resulted in two lesser nations that would have been more easily exploitable by outside nations) and was one of the earlier factors in the rest of the world taking us seriously as a nation.