Its the same monkey brutality we see in our ape cousins, just with more emotion and such behind it, along with more technologically advanced and organized militaries. Is it inevitable? For the time being, yes. Is it necessary? ...That, is a very good question, and one for which I have no answer. I do, however, believe that we are capable of, and will eventually achieve, being a species that's moved beyond petty wars, and whose major source of conflict are things like accidentally hitting someone else's cart in the grocery store. Will there always be conflict? Of course, humans (and living creatures in general) are so diverse that people, personalities, beliefs, and principles are bound to clash. Will we be able to minimize it, someday, to the point where it won't lead to organized, wide-spread chaos and destruction of human life? I don't see any reason why not. Species and societies advance all the time, people learn, they get better informed, they get better educated.
It'll probably come to a point where the entire species is so war fatigued, that we simply can't bring ourselves to continue these kinds of conflicts. While that'd be a...suboptimal way of reaching said goal, if that's what's needed to help us evolve beyond that point, then that's what it'll take. So long as it gets done, I doubt future generations will mind very much, so long as we don't end up royally fucking the planet in the process.