I realize this question can be more easily answered for post-Yugoslavia, but... I'm in the mood for a little macabre humor this morning.
Care to make a list for our continuing education?
Reasons for NOT going into Iraq (that make sense) 101.
Have at it.
OK, I will explain. (I wish I were paid for doing it).
The chief reason for not going to Iraq was that Iraqi regime (authoritarian secularist nationalism) was the expression of natural equilibrium for the entity composed of three disparate societies and located in the middle of Muslim world.
That is why USA under Ronald Reagan and Western Europe and Soviet Union supported Baath regime. This regime was the bulwark against Islamism and main hope for modernization of the region.
You see, democracy is a form of luxury, you can afford it when you are advanced and prosperous, either when you have large educated middle class or many slaves to support you (like in Athenian democracy). In a messy situations like XXc Iraq or European "Dark" Ages the monarchical or dictatorial power was the only VIABLE solution (with the exception of small rich city states based on commerce like Florence or Novgorod).
Now there are two most likely outcomes:
If dogmatic Wilsonian approach is followed the three divergent loose cannons will be released. Shiite South with strong ties to Iran and subversive impact on Gulf emirates (with large Shiite population), practically independent Kurdistan which will be on collision course with Turkey (Turkish south east is Kurdish), and Sunni middle in control of huge capital city without natural resources, trained in war and politics, bent on revange.
The second possible outcome is RESTORING of the equilibrium by bringing back secular dictatorship disguised by intense "democratic" rhetoric.
Ditto , especially "that make sense".