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.
You do realize that all of Star Trek was done to make money, right?
Making some sort of appeal that this film's profit motives are different than in the past is pretty clueless.
As far as the use of Khan goes, it's pretty canny. Abrams and his writing team get to use the most recognized antagonist in the Trek pantheon in their own sandbox. They get the benefit of recognition and the freedom to craft their own story. I'm very excited to see how Khan plays out in this very different timeline.