And, regarding your *sort of review,* it strikes that the view of war as necessity is fatalist, too [edit, I realize you are exploring that view and to some degree taking issue with it]: there are plenty of examples of problems solved without the kind of large scale violence Heinlein and others nod to. Also, that kind of view is often used to excuse mass bloodshed as a necessity. I suppose Tolstoy would argue the Great War (WWI) was a necessity to free Europe of its prior bonds, which, presumably leads to the Second World War to deal with the problems the Treaty of Versailles caused. Was it really necessary to kill, what, 90 million(?) people because the old monarchs couldn't check their egos? If so, yikes.
But it does remind me of a conversation I had with someone recently that is obliquely relevant to the end of the Russian monarchy. Some people (and often libertarians) like to say, "the market will solve the problem." That is essentially a universal truth if what you mean by market is kind of a social Darwinism. The problem is the market's solution is usually disruptive. For the taxi drivers of the world, it's ridesharing and you nod your head and think, ok, so that's a dirsruption for the cab driver, but good for me. Hooray for the market solution.
But for the aristocracy, absolute reliance on the "market solution" led to the guillotine and the Bolsheviks, neither of which is particularly attractive. "The Glorious Revolution" wasn't so glorious for the English monarchy. The lure of traditional liberal democracy is the idea that through the consent and participation of the governed, we can solve problems without resorting to large-scale bloodshed. Since the Civil War, the U.S. largely has solved domestic issues that way. India provides a pretty good example of even national rule changing as a result of liberal democratic values and process.
This is not to suggest that change in liberal democracy is easy or painless, only that you don't have to kill millions of people to get it. However, it only works if the people consent and participate, which requires that they have some ownership in it and believe it is to their advantage to do so. One of the more interesting facets to that is how property rights factor in. Things to keep you up at night.
On a interstate level, the proliferation of interstate trade, which can give countries a real stake in the stability of other countries, has some potential to pacify international relations. Indeed, the world has been a safer place since WW2 as "western" countries were united by trade. Again, the flow and distribution of capital are critical--and things to keep you up at night.
I suppose I'm trending way too far into politics here, but whatever. :-)