But from what I've seen on the Intenet since then and following fernwithy's lj comment and lianna_blanca's reply, I'm inclined to think that there's more to it than Colin Firth fan-aticsm.
I think the intense KK hate is the natural progression of the intense KK love of yesteryears. As the Goblin so aptly put it: "There's nothing people love more than a hero than to see a hero fall." It's one thing to praise an under-valued actress for her talent and range and beauty (there were a lot of fans who kept moaning and groaning about how she should have been cast as Padmé Amidala and Natalie as the decoy), it's another thing to praise same actress when she's a big star. Suddenly the same people are moaning and groaning about how she's not that talented, is a one-note actress and is too thin.
The problem with KK is that she's too much: she's too young, too pretty, too talented, too successful, too thin. It's our sad, cruel, flawed human nature to hate someone like that.