Democratization in recent years has not generally contributed to U.S. interests, and it certainly has not contributed to greater peace and security. From empowering Hamas to building up an aggressive nationalist demagogue in Georgia to boosting socialist “people power” in Bolivia and Venezuela to provoking ethnic conflict in Kenya, genuine democratic elections have produced a number of undesirable outcomes for the nations involved and for U.S. interests in their respective regions. The idea of “democratic peace” is a myth, and the politicization of ethnicity and religion that democratization has involved in many parts of Africa, Latin America and the Near East has led to terrible results. Why we should want more of this is a mystery, but like much related to the management of the empire this is something we are not supposed to challenge.
I would add that all of this is not to say that democracies aren't a good thing, or that nations around the world shouldn't move toward democracy, or some form of democracy, since I truly believe that despite all of its flaws, democracy is still the best of all possible political systems. However, what is lacking in all of the nations where the US has tried to impose it is both the rule of law, and a historical foundation of order and representative government. The United States was born out of the British history of a functional parliament, and traditions dating back to the signing of the magna carta. America was also a healthy group of colonies, with relatively high stability and rule of law.
Compare this to Iraq, a country with no history of liberty or representation of the people, founded in a region of the world that has been plagued with war, religious fueding, and totalitarianism in one form or another--or to Afghanistan which has only the tradition of tribal politics, and warlord feudalism. It's simply not good soil for democracy, and certainly not for imposed democracy.
I think a better means by which to export our ideals would be through example, through healthy trade, and through tireless diplomatic efforts. There is a time for force, for war, but it cannot be in order to instill something as fragile, and whose outcome is as unforeseeable, as democracy.