What is it good for?

 Israeli historian Yehuda Bauer:

DW: How has the current escalation in Gaza changed life in Israel?
Yehuda Bauer: It has changed it quite meaningfully, because over two-thirds of the country was under attack by rockets. Although the rockets have not caused a tremendous amount of damage, the whole country was decisively hampered in its economic, social, cultural and other activity.

Chinese intellectual Mozi from a little over 2,400 years ago:

When feudal lords entertain suspicion, enemies will be stirred up and cause anxiety, and the morale will be weakened. On the other hand, if every preparation is in good shape and the state goes out to engage in war, then the state will lose its men and the people will neglect their vocations. Have we not heard it said that, when a warring state goes on an expedition, of the officers there must be several hundred, of the common people there must be several thousand, and of the soldiers and prisoners there must be ten thousand, before the army can set out? It may last for several years, or, at the shortest, several months. So, the superior will have no time to attend to government, the officials will have no time to attend to their offices, the farmers will have no time to sow or reap, the women will have no time to weave or spin: that is, the state will lose its men and the people will neglect their vocations.

Human nature has changed so little that most of Mohist criticism of war still holds up today:

The rulers and lords of to-day are quite different. They all rank their warriors and arrange their boat and chariot forces; they make their armour strong and weapons sharp in order to attack some innocent state. Entering the state they cut down the grain fields and fell the trees and woods; they tear down the inner and outer walls of the city and fill up the ditches and ponds; they seize and kill the sacrificial animals and burn down the ancestral temple; they kill and murder the people and exterminate the aged and weak; they move away the treasures and valuables. The soldiers are encouraged to advance by being told: "To suffer death is the highest (service you can render), to kill many is the next, to be wounded is the lowest. But if you should drop out from your rank and attempt to sneak away, the penalty will be death without moderation." Thus the soldiers are put to fear. Now to capture a state and to destroy an army, to disturb and torture the people, and to set at naught the aspirations of the sages by confusion - is this intended to bless Heaven? But the people of Heaven are gathered together to besiege the towns belonging to Heaven. This is to murder men of Heaven and dispossess the spirits of their altars and to ruin the state and to kill the sacrificial animals. It is then not a blessing to Heaven on high. Is it intended to bless the spirits? But men of Heaven are murdered, spirits are deprived of their sacrifices, the earlier kings are neglected, the multitude are tortured and the people are scattered; it is then not a blessing to the spirits in the middle. Is it intended to bless the people? But the blessing of the people by killing them off must be very meagre. And when we calculate the expense, which is the root of the calamities to living, we find the property of innumerable people is exhausted. It is, then, not a blessing to the people below either.