So instead, Paramount chose to angle their promotion of the film omitting that little tidbit. There's nothing wrong with that. It makes pefect sense that Paramount would want as many butts in the theaters and as many eyeballs on those screens because means the picture is selling tickets. Why this is such a complex issue to comprehend is beyond me.
Thing is, the reason they chose Khan is because it's "what everyone wanted." You'd think if you're going to include "what everyone wanted" in the movie, you'd want to promote the hell out of it, not keep it a secret. Hell, at the very least they could have made John Harrison the renegade Starfleet officer public a lot sooner than they did.
I guarantee you, hearing "the Enterprise crew fights Khan" or "the Enterprise crew fights a renegade Starfleet officer" makes the movie sound a lot more exciting than "the Enterprise crew fights someone."