If peace came, then we'd have a lot of people out of work and money. We make money in war supplies such as uniforms and guns. We even make money in domestic issues such as crimes and prisons because someone has to guard those prisoners, someone has to make the handcuffs and we even make money by hiring those prisoners to do work for free or near free. Peace would ruin our economy which is undesirable.
I honestly don't think total world peace is ever possible, just because of the divided political minds that exist in the world. Humans have a selfish nature, and will always want more for themselves, which causes war. Love breathes into sacrifice, and sacrifice breathes into hatred. In war, people will suffer whom have nothing to do with the war, which causes more hatred. Life itself may be the source of peace and unrest.
Although it is unlikely, peace is still the desirable outcome for a society. It is true that wars can help spark some innovation, but they ultimately cost more than they gain us. Even in peace time, there will always be conflict that can drive society to improve itself and grow more functional.
I think that peace is desirable over war if that peace doesn't come at the expense of everyone's rights and freedoms. If "peace" is achieved by simply crushing the ambitions of everyone who might want to do something different from those in power, then it's not truly peace, but subjugation. Actual peace is when people are given the free choice and choose to live together without conflict.