She also filled a role as foreign relations advisor, & cultural attaché, which is something I could see being useful on the bridge. Granted, to be of value, she needed much more of that than the other stuff she did. I never had a problem with her duties, or being on the bridge, just that they never really represented either very well imho. Apart from Picard, she really is supposed to be the diplomat on board, as well as a mental health professional