I asked some of these questions and got an interesting answer (if I get any of the following "wrong" totally my fault).

The Iraq, Afghanistan, Vietnam, Korean wars are colonialism or imperialistic altercations where a paternalistic veneer overlays the conflict. Nobody wants a whooping but it's for your own good (how many dads have said this?). The reasons for this type of conflict and it's associated political troubles are varied but are put in a couple of bins. Political will of the aggressor is low (Korea), the actual reason for the conflict is not known or realized by the public (Vietnam), the conflict is a response to a historical precedent (Iraq).

In contrarian view to the imperialism and colonialism is punitive expeditions like Grenada, Panama, Haiti where similar issues of political will, through historical precedent existed. Even with similar issues the mission objectives were alliterated differently and length of conflict was entirely different. The political goal of nation building seems to be the thread that gets us into trouble.