I fully get ya, Horatio.
Yes, the one thing we really didn't get to see from Cumberbatch's Khan was that charisma to lead men and women...and yeah, the threat of what would happen if one of his own disobeyed him. No inclination that the people he tried to protect were "sworn to live and die at his command".
The only thing we saw in Into Darkness, as far as bending others to his will was his willingness to save Harewood's little girl, and you could see on his face that there was a horrible price to be named in return.
He did, however, display the cunning and cold logic worthy of Khan, especially given his knowledge of StarFleet operations.
He played the charlatan well. Just as Montalban's Khan was a man out of time, and he used that to his advantage to gain further knowledge and a sympathetic ear from Kirk and crew in the prime timeline, this Khan was a charlatan in that he brought himself to shed tears for the people he "held dear", and he got just enough sympathy from this Kirk to say "look, you help me out, and I'll do what I can to protect your people."
However, there really didn't seem to be much A to B to C to have the audience anticipate that Khan would eventually revert to his old stripes, and betray Kirk and crew. Kirk just kinda told Scotty: "Down him as soon as we have the bridge" on the basis that he figured that it wasn't Khan helping them, but the other way around. The only way that much of the audience would anticipate that Khan would betray them is if they had knowledge of the original Khan. I think that was the reason for the scene with Spock Prime...so for those new audience folk who didn't really know who Khan was, there was a basis for them to now say: "Whoa! Something's amiss here." Kirk just kinda took it upon himself to make a leap of logic, and presume that Khan was going to betray them. (I would gather he deduced this with Khan's disappearing and then reappearing again, both in the flight over from the Enterprise, and during their brawl with security on the Vengeance.)