The problem with torture in Pathfinder is that while in this world you have your law and order, even in the smallest redneck town. And there is always some way to make things right.
In pathfinder there often is no way.
If the lord of the land is an evil greedy bastard, and he has enough money to give him the power of law, than it is not so easy to get the proof needed to make him drop.
And than who is to take him down, and even further what will stop his friends of not killing your good-aligned ass with law in hand?
This is where torture can (in the eyes of my inquisitor) be used. When proof is good, when you know he is evil, when there are none other than yourself to stand up for the weak and wounded.
Than you get the lord of the land, find the paper with all the accusations you have, and the proof you have gathered, and make him sign it. Because in court there will be no justice, if you just turn your back the weak will still be broken by the man. But with a signed paper in hand, and the proof to back up your claims, than even the highest, most powerful landlord can be sentenced to death.
If all that it takes is for one man to torture the final signature out of him, to ensure the safety of the land, to ensure the power of unbribed law, than it is needed.
"Lawful Good is the best alignment because it combined honor with compassion. Also if someone gets in your way and they are wrong, you can torture or beat them until they give into your demands."