I think Troi makes more sense on the bridge if you think of her as more than the ship's psychologist. If she's there to advise the Captain and provide a sort of big picture perspective on whatever mission the ship is currently on and whatever forces the ship is interacting with, I think she makes lots of sense.
Someone once compared the idea of a "ship's counselor" to the "political officer" on Soviet ships back in the day. While I don't agree they are quite the same, the analogy kind of works for me. "Ship's counselor" gets a little Orwellian if you think about it too hard.