Very good point. In that sense, torture did "work". It also explained why Bush and Cheney's CIA and military had regular agents and enlisted personnel doing the torture, instead of the previous practice of entrusting it only to a few agents who could be counted on to keep it secret.
I think it was also intended to serve Cheney's agenda of rolling back the reforms imposed after the Church committee reports, and his publicly stated agenda of asserting greater executive power for the president than the constitution actually provides.
Everything Dick Cheney has ever done in his life, I am convinced, has been calculated to make him look macho, tough, in charge, powerful and, above all, patriotic. I imagine his emergence from the birth canal was orchestrated to look as though he had been "liberated" from some terrible gulag.
People like Cheney care very little, if at all, for reality. What matters is
how they are perceived. If they look tough and active when torturing people, regardless of poor results, it still
looks as though they're doing something. If it doesn't work, oh well, blame it on the liberals and their weak-minded opposition. I mean, look at them, they'd rather read these evildoers their rights and give them therapy than actually stop them from doing harm, right?
Everything is a mind game with neo-cons and it's a two-pronged attack: give the illusion that you're doing everything you can to stop these guys who
want to hurt us(I mean, who doesn't like a Marlboro Man/Dirty Harry/John Galt/rugged individualist?) and make sure the opposition looks like a bunch of pussies (the more sense they make, the weaker and more un-American they are). Of course, as you said, it's a blatant power-grab. The weaker and more scornful you make the opposition look, the more likely people are, you suppose, to continue to give their support to you.
As I have baldly stated in previous posts about torture: bottom line, it does not work and it never will.