Maybe the writers didn't like her as a character. She was usually the "straight man" to JD and Turk goofing off. There was the love triangle with Cox, but that fizzled and went nowhere. She sort of became best friends with Elliot, but they didn't seem to have any genuine chemistry or shared interests, so it always seemed forced.

She did kind of exist just to make Turk's life annoying, especially in later seasons. They had a very lopsided relationship.