Such a vague generalization that doesn't give Star Trek any distinguishing features. Any genre of stories, whether they're books, comics, films or a television series can be just about the characters. It's like saying "Any film can be in color", but that's not all it takes to be good. Yes, characters are important, but so is the story. If you're going to tell me that your story is actually about something, you've got to meet your audience half way. When it comes to how the story relates to the characters in STID, the story always took a backseat in order for things to happen even if it didn't happen that way earlier on. One moment a ship's sensors can automatically detect when a torpedo is armed and when it's about to explode, but later on it won't. You're ignoring your own story just so something can happen later on that this moment would have prevented.
A good writer can write a story that gives the bad guy a much deeper motivation to his character outside of the plot having him just be the bad guy. Khan's motivation for going into space was so he and his people could find a new world that they could build an empire out of free of humans who don't share their view on world order. In STID, Khan's motivation for going into space was because he hoped that things would one day be different.... What? Not even the writers cared enough to elaborate on what this "different" thing was. The original Khan's quest for revenge in TWOK comes from the fact that he spent 15 years on a planet that turned to hell which killed 20 of his followers and his wife. This adds much to his character because for the second time in his life, those that Khan deemed inferior have put him in a situation where everything he had hoped to gain is now lost. Only instead of a chance to build an empire, all he wanted was revenge. This new Khan's quest for revenge comes simply from "assuming" that Marcus had killed all his followers. That's it.