For me, it always comes back to "Why Khan?"
Even among the ridiculous predictions, there's frankly more original thought than saying "this is the rebooted Star Trek 2, therefore Khan is expected and then that's what must be delivered."
Even the ones which sound silly based on the way they happened before, I think different universe, different hand dealt or different roll of the dice and potentially a different outcome.
Seen "Elementary, Dear Data"? Then that's where I often think Star Trek is at right now. Data programs a Sherlock Holmes type adventure and the extent of his deductive reasoning is simply to recognise character/plot/situation elements from existing stories that Arthur Conan Doyle wrote, randomly cobbled together to appear new. Then again, what does the computer do in order to create an adversary capable of defeating Data? It basically adds a third dimension to Moriarty, Holmes' greatest enemy. Access to a reality he didn't have on the page. But at least he operates on a level the original version couldn't.
The argument in this instance, would appear to be Khan is remembered as Kirk's greatest enemy and so, that needs to be proven all over again, to satisfy somekind of audience expectation.
Khan ruled the world, escaped, woke up in the future, briefly tried to take control of a starship, was defeated and sent into exile. Years later he eventually escaped again, blaming one man for his loss and after another conflict, was defeated and blows himself up, in one last attempt at vengeance. It costs the object of his grudge, a very high price in order to escape.
I mean, WOW! Imagine if Harve Bennett had latched onto a different one hit wonder Original Series villain. No disrespect to the memory of Richardo Montalban, but there were better episodes than "Space Seed" to elaborate upon and it's only really The Wrath of Khan which elevates the episode's status. The successful formula set by that film in my opinion, is how to take a character established in the Original Series, preferably one who owned the story in which they appeared, sum them up in a single reintroductory scene and then add further flesh to their bones with a personal motivation to want a rematch with Kirk and/or other members of the Enterprise crew. Their coming back for more doesn't even need to be about revenge, in a universe where they haven't even met.