The people in many countries go through hell because of the existing government. Since democratic governments seem to have a high success rate, why not promote it and help citizens lead a better life?
Also consider that war and conflict is very common between countries these days. Most of these countries are NOT democracies! If democratic countries manage to maintain peace, there must be something that they are doing right.
Democracy should be a choice, we should show other countries how to achieve it and assist them when they want the help and or ask for it, but it should not be forced onto them. That would be the opposite of what democracy stands for and it would be counterproductive.
Imposition of democracy implies unwillingness on the part of the target nation, whether it be the current government resisting the change, or the people, or both. Democracy in its purest form does not really exist in the world today as far as I know. Maybe it might exist in a small family somewhere, but that is probably the extent of it. Representational democracies, in which the representatives are selected [hopefully by the people] to take the peoples' place in a democratic forum, do exist. The USA fits into that category. I do know how democracy COULD be imposed on a nation, on a people, on a government. It the impetus is not voluntary and from with, how could a democracy come from that? Democracy imposed would be definition have to continue to be imposed to last. And that hybrid sort of government would not seem to conform to any definition of democracy in my way of thinking. It might be a benevolent dictatorship but I don't think it could be a democracy. So no, I don't think democracy should ever be imposed on countries... as the outcome would not be democracy but some sort of captive government. The opposition would always be present. The government would be at war with itself. The moment the restraining hand let up its grip, the government would likely morph back to its former identity.