"Why do people hate Nemesis?"
Uh, because it treated the audience as though they were dumb founded idiots. Anyone who says they're making a Star Trek movie for the general audience and not for Star Trek doesn't really understand what they're talking about. Sacrificing many great stories for the sake of more audiences only weakens the film.
Stories ignored:
- Picards artificial heart that would have given Picard a nice edge in the whole "events of one's life" argument, and possibly tell Shinzon that he has the capabilities to be more than what Picard is knowing what mistakes were made. Good potential, but completely ignored.
- Sela's involvement. You would think that someone as important as Sela would have wanted to become a part of this move against the federation and Picard, but instead we just forget about her. Not saying she should have been a huge part, but a little something would have been nice.
- No mentioning of Lauxanna Troi and her reaction to Troi's wedding. She always made a big deal about it in the series, but I guess if they can forget about Spock's parents in STII, they can forget about Lauxanna.
- Lore. Honestly? No mention, warning or concern? He wasn't vaporized to atoms in the series, he was just deactivated.
- No Spock. Ya, I know they said he wasn't crucial to the story, but if they're making a story involving Romulas and it's potential for further peace with the Federation, wouldn't Spock have to become a part of that story to bring his story full circle?