When we talk about iconic stories in Star Trek, many go right to Star Trek II: The Wrath of Khan. For good reason, it's one of the best films in not just Star Trek history, but science fiction history. We're not sure where it'd rank against the hoi polloi of the film industry but we know it's up there. Even if the "experts" don't agree.
It's a tremendous movie and does something that few could do. They brought back a story from the original storyline and expanded upon it, but did it in a way where you didn't need to watch the original show to understand the point of the film. Khan Noonien Singhs' debut on the original series episode "Space Seed" was a tremendous one, but it lacked something.
So when the story was re-visited it in Wrath of Khan, director Nicholas Meyer knew what he had to do; keep Khan and hero James T. Kirk apart. After all, if you try to have Kirk fight a genetically altered being like Khan in a fistfight, Kirk will lose.
Meyer knew that, so he kept them apart. In doing so, he ended up never putting them on screen together once, a fact that wasn't lost on Meyer as he spoke to TrekMovie.com.
"Well, I don’t know how good I am at analyzing my own stuff. I do know that they wanted to have a mano a mano, a fight between Kirk and Khan. And I said, “Well, they tried that in ‘Space Seed’ and it looked phony and stupid to me.” Khan is a superman. Kirk wouldn’t stand a chance against him. It just seemed kind of corny… So I resisted the idea of this mano a mano shootout, or whatever it was supposed to be, in favor of cribbing from one of my favorite movies, The Enemy Below which is a World War II duel between a destroyer and a U-boat, and Robert Mitchum, who’s the captain of the destroyer, and Curd Jürgens, who is the captain of the U-boat, they never meet. It’s just their weapons that meet."
The decision to keep them apart makes sense when you remember that Khan would win any fight with Kirk. It's why when the franchise revisited the concept with Into Darkness, Khan wiped the floor with everyone he was put against; save for Spock.
Vulcans are stronger than humans, making him a far more formidable fight for Khan. How they wrote Khan and how the crew faced off with him was one of the better aspects of the film. It reflects Meyer's work with the original story, which in turn further galvanized Meyer's version.
Any other director may have fumbled Khan, all for a more flashy fight scene, but because Meyer didn't, the villain was protected from being unnecessarily exposed, leading to a climatic finish that felt earned. It's a major reason, if not the core reason, why the film is so beloved.
If anyone else tries to do Wrath of Khan, likely, the film won't likely become the cultural touchstone that it is among Star Trek fans.