The issue of torture is a real and present threat to both our national security and our national identity.
If our government does not prosecute those in the government who ordered it and those who performed it, then we the people, from whom political power flows in this nation, will become complicit in war crimes. Because our laws define our nation, our combined flaunting of them will effectively destroy the country. We will no longer be able to call ourselves “Americans.” Other people will then rightly be able to brand us as international criminals, subject to the harshest of punishments, and we will have no one to blame but ourselves.
Aside from the issue of responsibility, torture is fundamentally wrong, diminishing the moral standing of those who execute and support it. This judgment draws from the fact that it involves harming people who have not been proven guilty of any crime that warrants such harm.
Torture is also stupid. It has been proven ineffective at getting reliable information (its supposed point), and very effective at causing others to retaliate against unwarranted aggression against someone they care about. Note that this is similar to preemptive war, which penalizes many more people for their association with potential attackers.