... but it was hardly desirable. At the time of the breakup, millions of citizens considered themselves Yugoslavs first. Tensions did break out, but spiraled out of control only once the country split up. Yugoslavia in 1991 was comparable in wealth to Spain and Portugal and was on track to join the EU within a few years - that has been set back by decades, along with hundreds of thousands of dead.
And if Yugoslavia was an artificial state, is the successor state of Bosnia-Herzegovina any less artificial?
The point is that out of all those partitions that I named, in each case the most violent phase occurred AFTER the countries were partitioned. And ultimately, the successor states were less well-off and more embittered. Old economic networks were ripped apart, families were divided, and in many cases relations are STILL bad between the two communities and the successor states. By partitioning a country, the new nations have no incentive to be pluralist or resolve communal or ethnic tensions and what previously were internal disputes became long-term international conflicts.
Moreover, most Iraqi Arabs don't want to see the country split up (although the Kurds would like to go). Iraq may be a creation of the British, but so are a pretty large chunk of countries in the world. Granted, I have not personally spoken to any Iraqis or Iraqi-Americans, but if you read interviews with ordinary Iraqi Arabs and watch documentaries, the striking thing is how much people identify with "Iraq" despite it being a creation of the British. A professor of mine noted the same dynamic in Jordan - a completely artificial state in which the inhabitants nevertheless were fiercely nationalistic. Even in Iraq, during the Iran-Iraq War, Iraqi Shi'ites were strongly opposed to Iran, something which fed a lot of the resistance to Iran in Southern Iraq.
And again, where are you going to draw the lines without creating a bloodbath? What's the largest Kurdish city in Iraq? Baghdad. Mosul, Kirkuk, and Baghdad are all highly mixed, and even in regions where one group predominates, another group often forms a large minority (plenty of Sunni Arabs in the South, millions of Shi'ites in the middle and in Baghdad, Turkmen, Assyrians, and Sunni Arabs in Kurdistan).
But don't take my word for it - read this interview with Robert Schaeffer about the problems with partitioning countries in general:
http://www.thenation.com/doc/20040329/coleOr if you need more convincing that splitting up Iraq would just perpetuate the problems, read this article by Juan Cole:
http://www.thenation.com/doc/20040329/cole