I think hiding Khan was a mistake. I don't see where the movie really gained anything by keeping it a secret. The reveal itself was kind of "meh." The artistic merits certainly don't outweigh any publicity gains they might of otherwise had.
And, without any proof to the contrary, have pin that blunder on Abrams.
Heck, you can argue that the 2009 film is darker due to the destruction of Vulcan.
They also liked to play the "it's a very different kind of film" card a lot. Except it wasn't. The plotting/pacing was almost identical to the first one.