In reply to your response to my last post...
Certainly TWOK could've been written to provide a meeting or confrontation between Kirk and Khan, but I am a loss to say how that would've pulled that off in the confines of the film/story that we got. And they didn't have to write Khan as so far gone as they did in TWOK, though I do think his madness increased as the film went on.
As for hurting Kirk, it didn't have to be solely physical pain. Khan realized that Kirk was goading him, that Kirk wanted him to beam down to the asteroid so he didn't. He understood at that point that he could wound Kirk more deeply by killing his friends and destroying the Enterprise while leaving Kirk stranded and helpless to prevent it. By the end though Khan had become so unraveled and hellbent on getting revenge that Kirk's taunting worked, and when Khan took the bait it sealed his doom.