Her and Riker were the ones chosen to be there for their attractiveness. It was a showbiz rule that at least one female character has to be fuckable and in this case we got a male character too. Too bad the writers created such weak episodes for her, like S2 E1 "Child". I agree that they didn't think through her plot spoiling abilities properly. She even senses "a unifying consciousness" from Moriarty, a holodeck character made of literal photons of light... I wonder how much cocaine those writers were doing in the 80s...