you could play with a kid if you have one multiplayer in your house
there are a few exploits you can do with 2 players in a wing to get to destinations quicker
you get an extra pip for shields / engines or weapons if set for multicrew.
The above 2 things didnt interest me however i just wanted the possibility to see a bum on a seat next to me in my ship (one of the major failings which is surely an easy fix is the fact our ships are empty and lifeless imo..... - probably wont notice much unless you play in VR)
it boggles me FD never implemented ships crew. They were meant to, it was in the design plan as a soon after release addition.