welp yes with the unlockable ships and guns I too wished my Crew could share them with me when I was a captain. but since leveling doesnt take that much time, I don't really care.
I would encourage that a crewmember can be Pilot if the captain chooses engineer or gunner.
For the ship decoration and decals I think that they barely matter; if you don't intend to pilot, then you simply shouldn't buy them. There is plenty of costumes, hats, goggles, dyes etc for gunners and engineers.