Please don't spam and get off topic in other threads, like with the KH2- Love or Hate it thread.
I hate Kairi because she's useless, underdeveloped, acts cold and uncaring towards Riku and her other friends who aren't Sora, and, in the end, it's not her that's important to the storyline of KH. It's her status as a PoH. She could have been replaced by anyone and it still would have come out the same, or perhaps better.
If you would like a more detailed or better explanation as to why so many hate her, perhaps you should visit the Kairi Hate-Club. We have a list on the front page that deals with why we hate her. There is also an essay that the founding member wrote that tells very well why Kairi should not be liked. You can find it in her signature.