The answer is two fold. Firstly, as part of her contact, Gates McFadden was promised several episodes over the series that centered on her character of Beverly Crusher, which only happened once or twice a season leaving her character underdeveloped. Secondly, the creators of the series were stretched very thin during the last season of TNG with the ongoing filming on Deep Space 9 and starting both the TNG movie and Voyager. This lead to some very poor quality control in what scripts were accepted.. It was submitted by a totally unknown script consultant who ripped off a very bad Ann Rice story about Scotland and an incubus like creepy ghost.