I believe it is possible to promote just governance in developing countries without any cost to the developed country or at least minimal cost. I believe developed countries do have a moral obligation to promote this when possible. It is obviously the socially responsible thing to do and this world needs more social responsibility.
Yes, we are morally obligated to promote just governance in developing countries. It's kind of like being a big brother or a big sister - you look out for the youngest in the family. As fully developed countries we need to do our best to ensure that the people in developing countries are treated humanely.
The world lives and dies by revolution.
Basically, unless the whole world is on the same page with fundamental human rights and freedoms, there is always the chance that certain factions will try to spread their views. Our history is fraught with civilizations growing, evolving, dying, being replaced.
In that sense, to fend of that possibility, it is likely in our best interest to maximize personal freedoms worldwide. However, the catch 22 of freedom seems to be that, as we see with the SJW crowd, we are attacked even internally with respect to our personal freedoms. Even the fundamental ones like freedom of speech.
We stay stalwart in protecting our freedoms, or eventually we will be overtaken. Sad but true. And definitely kind of cynical.
Why should other countries have to police the world or promote a just country. If they become an issue then, bring in the troops. I think right now its everyman for themselves, it's not up to the world to justify the means for everyone else, they need to do it themselves.
Developed countries have no obligation, moral or otherwise, to promote anything in developed countries. The United States has done that for decades, it's called imperialism and interference. If we were truly interested in promoting just governance in developing countries, we would promote it in our own countries first. Something in the Bible about removing the plank in one's eye covers this, I think.