How many of our soldiers died because some Iraqi shmoe who didn't want to be fighting in the first place, who would have surrendered without a fight, decided he'd rather go down fighting than be tortured or sexually humiliated?
How much intel has been lost because said schmoe, who would have spilled all kinds of beans if asked politely, went down fighting just to avoid being tortured?
Treating prisoners well is the worst thing you can do to enemy morale.