Rehash is a fair criticism because it makes the franchise seem one note. Yes Nolan's use of the Joker was amazing even though it had been done in 1989. The other side of the coin is Lex Luthor ALWAYS being used in Superman movies. The Man of Steel film is breaking that trend. However when you use and reuse the same villain or plots over and over it makes the franchise seem stagnant and uninteresting. Batman and Superman have many other villains, but the Joker and Luthor are both the most recognizable. The same thing can be said about Trek. The Borg, Klingons, Romulans are Trek's most recognizable villains. So the idea to capitalize on their notoriety is what drives the decisions to use them to get patrons in seats in theatres.
With STID we have a third movie in a row that is thematically similar to the TWOK. The other two being ST 2009 and NEM. The fans asking "can't you do something else?" is a fair question.
Thank you. I'm getting a little tired of recycled stories. It seems to be an epidemic in Hollywood as of late. Star Trek is a story that takes place in outer space. If a writer can't come up with something original with a whole universe for a playground then he should give up the profession.
At least do something we haven't seen much of like the Gorn. Please no more Borg or Ferengi. And if they HAVE to rehash a Star Trek story, do something different. Khan wasn't the only good story told in the original Star Trek.