I mean I'm really trying to understand where this interest in bringing back Khan is coming from. Can someone explain?
Same exact reason why they brought the original crew back. You've got be somewhat delusional to think that Trek09 was a
DIFFERENT and FRESH take on Star Trek, because it wasn't. Different and fresh wouldn't have involved the original crew, the Enterprise or that timeline.
Let me ask you. When Batman Begins ended with hints that the Joker would be the next villain, did anyone whine or complain that the Joker shouldn't be in the next film because it wouldn't be different or fresh? I sure don't. In fact, the character, the writing behind him and the actor playing him were hailed as some of the best Batman material ever.
Now, you're probably going to say
"Batman is a different series entirely. It's about good guys fighting bad guys. That's not Star Trek.", I'll just say that you're half right. Star Trek isn't just about good guys fighting the bad guys. However, have you seen the trend that the Star Trek movies have been on lately? 80% of all the movies have a concrete villain in it that the good guys must fight to stop. I mean, come on? Star Trek Nemesis and Trek09 both dealt with bald headed villains who had something to do with Romulas and they both wanted to destroy Earth for very vague and very plot convenient reasons. That's not different or fresh.
What I'm basically getting at is this. Khan being brought into the sequel or any future Star Trek story is not a bad thing. If he was going to be the baddie in the next movie, you can bet your rear end that nothing will play out like it did in either Space Seed or Wrath of Khan. Think about it. All those posters who say it will be a remake of The Wrath of Khan simply because Khan will be in it makes no sense. The story for Wrath of Khan had 15 years of development for all characters and lots of circumstances between those years brought everything to TWOK. There is no way the sequel can possibly be a remake of TWOK.
I'm certain that if Khan was to be in the sequel, things will probably feel familiar, but guess what? We're dealing with the original crew, the timeline and the Enterprise. Familiarity is inevitable and required. So save yourself the trouble in arguing that bringing Khan back would be unoriginal, because unoriginal characters and stories is all we're going to get.