It was just the first series (the character was killed off in S1e23 “Skin of Evil”), and although part of her complaint was that the writers didn’t seem to know what to do with the character, the writing as generally just awful for the first couple of seasons. Crosby was actually the center of what is generally regarded as the worst (or at least, most explicitly racist) episode of The Next Generation), “Code of Honor”:
Michael Dorn refused to appear in the episode, and several cast members have expressed regret about the story.
At least Crosby chose to leave the show; before production began on Season 2, Gates McFadden was informed that her character would not be returning, apparently because the producers thought she was an uppity bitch for objecting to some of the terrible writing that made her both a terrible mother and an incompetent physician. Her replacement, Diana Muldaur, was never made a main cast member and apparently clashed with the other cast, so they brought McFadden back for the rest of the run and even gave her character a significant role in a few (if generally terrible) episodes, as well as briefly appearing in Generations only to immediately be shoved off the deck of a holographic schooner, and then disappear for most of the rest of the film. So, not literally “killed off” but sent to a kind of actors’ purgatory where her character basically functioned as an exposition dump, even in cases where it really didn’t make sense for her to do so.
Stranger