Funny enough I find such a position on a ship lost in deep space very important.
Oh, an ACTUAL morale officer with mental health credentials would probably be a good thing to have. A random alien you picked up on the way to getting stranded? Ehhhhhhhhhhhh.
(I'm only half-serious, in an actual stranded-in-the-Delta-Quadrant situation I'm sure you'd take all the help you could get, but you probably also wouldn't have 400 shuttles and an unlimited supply of photon torpedoes, so let's just say I don't think the show did a great job of justifying Neelix's importance and leave it at that)