Frankly, I think it comes down to the writers didn't know what to do with her character, which seemed to be a regular problem during the 24th century years-- the predominantly male writing staff had trouble writing for women characters. Denise Crosby left because she didn't like the way the character was being written. Gates McFadden got canned because they were boxing themselves into a corner with the Picard/Beverly relationship. Troi was seldom used effectively and apparently there were discussions about writing her out of the show too. I hope McFadden charged them plenty when she was re-hired.