A Balkanization of Iraq might not be a terrible outcome if controlled. Say a loose federation of Kurdistan, Mesopotamia (Baghdad) and so forth. Probably wouldn't be very stable, but it might be a start like our own Articles of Confederation were.
Only reason that we have resisted allowing Iraq to break up till now is the threat from Iran. Iran appears ready to fall apart again, as it periodically does.
Yet it left an outdated ineffective system intact, like the Fallujahn mini-Islamic state, with a population without hope of competing with the West. And communism was what followed.
We could afford to leave everyone of those nations you listed in the dirt because the world was a lot smaller place then. Notice that each of the islands and nations that TomasUSMC listed as actually being defeated are not on the list of world hell-holes and communist states like the ones you listed.
I think that balkanization of Iraq would not be a potential disaster only if we defeated each unfriendly part. Otherwise, were still left with untouchable places for terrorist to train, operate and float between as we play monkey in the middle.