The subtext on the original timeline was that Kirk was rewarded for his cheating.
Khan is the most iconic villain in Star Trek. The role MUST be played by a big name actor.
None of the other more iconic characters were played by Big Name Actors. Why should Khan be any different?
The heck I know or care about just the movies. My point is that the Klingons and the Borg are overused in Trek lore in general. There are many races that could be pulled from different eras and improved. I'd rather the Cardassians be fleshed out.
Nero sucked partly cause he could have been any other race from any quadrant. There was nothing Romulan about him. That's what the movies need to be doing.
I'm not sure the movies *need* to be fleshing out massive amounts of lore. Nero substance, which could have been given many different ways.
Oh villains, any Khan-like person will do, imho. If it's Khan, if it's Tor/Kor (who, theoretically, should have been killed by Nero with the Klingon Fleet), they need a military mastermind.
If he's that way because he's genetically engineered, well, that could be cool, and with that kind of 'perfection' he'd be pretty ideal to take on Spock and Kirk at once. And perhaps he might have the original "Number One" by his side? Perhaps he'll be Federation? or Rogue Federation... lots of ways to go with Khan in an alt universe.
If he's a gifted member of another race, we have lore building to do, and the, um 'lamestream' doesn't take to well to that. The scene with Klingons and Nero in prison? Just 'too confusing' for the public.