He's just a great character -- bullheaded, violent, moody as hell, but instinctively knowing more truth about the world than all the "civilized" men he meets. He's unsophisticated -- but that also means, in Howard's eyes, that he's uncorrupted. Howard felt the natural state of mankind was barbarism, and Conan is the epitome of that -- untainted by the decay of "civilization."
-KURT BUSIEK