Just so you know, the other movies took liberties with the comic book history. No, the Joker didn't kill Bruce's parents but like somebody else already said, that guy Joe Chill did. That's one of the things that always bothered me about the previous movies.
And as for everyone else being annoyed with Katie Holmes' part in the movie, they say that because either a) they are annoyed with the publicity she's getting right now because of her fling with Tom Cruise or b) because they were annoyed with her during her Dawson's Creek days.
Now, putting the publicity she's getting aside and never having watched Dawson's Creek in its entirety, I can safely say that Katie Holmes had too small a part to be annoying. Also, the character of Rachel Dawes (even though she doesn't exist in the comics) had its importance in the film: it was the only character that confronted head on Bruce's need for murderous revenge on Joe Chill. She's the one that told him that it's up to the law to decide the fate of criminals (weither they live or die) and not him alone. She also told him that Gotham was worth saving, so that's why I didn't find the character annoying or unnecessary.
