In my opinion, one of the best ways to make a crew feel more attached to their ship and add a more interesting game experience would be to add ship variety. Each ship is just a little bit randomly or customizably different. Whenever you spawn in a fresh ship it will have slightly different characteristics from the last. Maybe a bit longer, a bit wider, a bit more durable, an extra cannon or two, a bit faster, etc. It would add a more interesting combat experience to the game, and could make a crew feel more attached to their ship. Obviously, the effects wouldn't be enough to make the ships unbalanced, but it would still be enough to spice things up. Also, the ability to name your ship would be cool.