I agree with SlashFilm's Germain Lussier on this one
The big question is, would those numbers have been any different had they handled the reveal differently? I feel like the answer is “Yes,” but on the dark side. Had Abrams came out last year and said “Khan is the villain” the likely response from non-fans would been alienation (“Who is Khan?”) and fans might have felt betrayed (“I don’t want to see another Khan movie”). Plus, that big surprise, even if it was mostly ruined, surely sold tickets as people wanted to see the answer for themselves. The mystery helped drive buzz and discussion about the movie, plain and simple.
Abrams might now think keeping Khan secret was a bad idea, but it was likely a bad idea that worked to their advantage.
Ok, erm, why would the general audience have been put off and asked „Who is Khan?“, but they weren't put off and asked “Who is John Harrison?“