(1) the CIA did some truly horrific stuff to detainees -- wallings, waterboardings, sleep deprivation, threatening their families, etc. (Specific quotes are in rdtsc's comment at https://news.ycombinator.com/item?id=8723834 ).
(2) the CIA systematically lied about and hid information about what they were doing from other parts of the government -- from the Senate Intelligence Committee, the FBI, the State Department, the Office of the Director of National Intelligence, US ambassadors in countries that housed detention facilities, etc.
(3) the CIA didn't provide its operatives with training in interrogation until months after the program started, didn't have facilities in place until just shortly before they took custody of their first prisoner, had very little oversight even within the CIA itself (see finding #12, page 17 of the pdf), and otherwise seemed to be flying by the seat of their pants. So they weren't even making decisions in a coherent, systematic fashion.
(4) all of this horrific, lied-about stuff... didn't even work. They weren't saving lives, and they had plenty of reason to know (before, during, and after) that the techniques wouldn't/weren't/didn't accomplish anything of value. So even firm believers in "the ends justify the means" don't have a leg to stand on here.