I will say, though, that I would have loved a scene in the beginning of the movie of a starship discovering the Botany Bay. I think that would have been more fun than the unnecessary John Harrison "twist" in the brig. "I'm not really John Harrison. I'm actually Khan!" Who cares? Just have him be Khan from the get go.
Yeah, the reveal was nothing more than just an "ooh aah" moment. It had no impact on the story, it had no impact on the characters, it has no impact on casual viewers, and the only impact it has on fans is fan service.
I agree with this and the original post that I would've liked to see a lot more back story, but at what point does that come at the expense of the other characters? I dunno, maybe they could've just made the movie longer, but I'm sure they had a time they had to keep it under. I certainly enjoyed it enough that I wouldn't have minded it being half an hour longer.
I don't even think a lot of backstory would have been needed. Just an extra quick scene or two of the Botany Bay being discovered. Show some Starfleet officers opening a cryotube. You don't even necessarily need to have dialogue. Just show it happening.
Although I guess that may have eliminated the surprise of "OMG there's people in the torpedoes!"