The torture policy was Cheney's baby, not the military's. They resisted, as my email in-tray over the years is testimony to. Cheney himself told us when he warned us of his walking over to the "dark side" what he was going to do, and a pliant, ignorant, overwhelmed president with a sadistic streak was powerless to resist, even if one clings to the hope he might have wanted to. Why torture for Cheney? I cannot know for sure, but suspect it was a way to gain some personal traction against an amorphous enemy that had no territory to defend and no army to destroy; it was a means of feeling in control; it was a way to reverse what Cheney believed was the neutering of the post-Watergate presidency; it was revenge; and it was secret, allowing Cheney and his small circle total control over the bodies of individuals they wanted to penetrate and destroy.
Fatally, it was also, according to the Senate report, a way to coerce evidence of an al Qaeda-Saddam link. Remember that the Bush-Cheney techniques were most aggressively used by the Communist Chinese to extract false confessions. These false confessions legitimized the torture and provided the justification for the next torture. This is the Imaginationland some of us have been worried about for quite a while now. Once you have abandoned the rule of law and placed your trust in the hands of human beings with the power to torture, there is no returning. All you can do at some point is turn the lights on and see exactly the human wreckage and reality that remains.