This isn't some off the books CIA wet team opp. It was planned and signed off at the highest levels. John Yoo, who wrote the torture memos, is a professor at Berkeley. That's how mainstream this was.
Furthermore, the people signed off on it. Not just through our Congressional representatives. Not just because we re-elected the politicians who did it. The public supported it directly. We've known for a long what was going on.
Prosecuting only the people who carried out the orders is cowardly.
You'd have to try Bush, Cheney, Gonzales, a bunch of high ranking DOD and DOJ officials, a bunch of Generals and other officers, Congressional leadership from that era, and former CIA directors too.
"Just following orders" didn't work at Nuremberg because we were trying the people who gave the orders too.