I think this is prevalent because of how many autonomous groups, or groups that desire autonomy (not even nations, really), in such a small area. It almost forces tensions to be high, because of all of the stepping on toes going on. I know there has been conflict for centuries in the middle east, and an end is still not very plausible, as well as in many parts of the world. I think the world has gotten too small, truthfully, for the amount of people and different groups that live on it. If people would be willing to move to another location and groups were more spread out, and utilized all the space of the world, it might work. But, no one wants to leave their land for various reasons (tradition, religion, status quo, etc).
I wonder though, what caused it to begin? And can it ever cease? Hobsbawn mentions that in the 1870's and before there wasn't even really much thought to tensions and large-scale conflict, but since then it has escalated and deescalated, but never really stopped existing. So how then did it begin, and can the same means be approached and ending it? As globalization becomes a universally shared goal, can we finally lay down our arms and begin to demilitarize? The sad part is, I don't really believe it's ever going to be possible.