Here's the thing: Abrams and his gang of writers made this movie for the mass audience, not for us. In doing so, they decided to retell the Khan story.
Every fanboi I've seen is upset. Abrams & Co. don't give a shit that you're upset. They wanted to use Khan and they cast Cumby because he guarantees good gate.
So cut the crap. This is about money and Paramount making a return on their investment in Bad Robot. Enough of the Sheeple will see this film and it will work for them for Paramount to greenlight a third film with Cumby back as the Khanster.