This I don't understand. Because if Vivi or Bon Clay ever found themselves on the Thousand Sunny I almost guarantee they would be permanent straw hats. And What exactly about Jinbei makes him not a straw hat? He has a dream, a dream of fish men equality. That seems like dream enough.
First, I see what you did there.We might not see a 10th crew member ever. It's already getting hard enough to juggle nine main characters in each arc, and all the important crew positions are filled. Lookout and Helmsman can be filled by whoever's free at the time.
If we do get a 10th crew member, it probably won't be anyone with an official role. Maybe something like a Quartermaster/someone in charge of keeping track of supplies, a Trader to help sell loot, or an ambassador type person to help with those Diplomacy checks the Straw Hats keep failing. Maybe even something like a Butler or Maid to just clean up the place. I don't know, I'm reaching for straws. I do hope we eventually get a Fishman or at least a Merfolk as a crew member, just because I really like the race, though there are other races we could potentially see too (Dwarves, Minkmen, Longnecks, Long-arms, Longlegs, etc.)
Second, I'm pretty sure Nami is the quartermaster, as she's in charge of navigation and managing everyone else's craziness. She also has a firmer hand on the supply side than just about anyone else, and runs the day to day activities of the crew when Luffy is too busy being crazy. After all in true pirate style the Captain is in charge when it comes to battle, but he doesn't run the rest of their lives.
However I do hope we see more Strawhats. Because gaining crew members is part of what has made the story so much fun. And it would be a shame if the ship didn't pick up enough talent to fill the Sunny up after they switched ships and everything.
If I might ask what qualifies as a Strawhat to you? I always thought it was the dream, and Jinbei certainly has that. Samurai guy, unless his son get's taken to the far corner of the world... does not.
Funny you should say that...Which is not relevant to my point
Scholars and explorers sometimes were on ships because they needed ships for their expedition. Darwin was not a pirate, was he?
All I'm saying is that 'there are no roles to fit in the ship' is not an argument against anyone joining, since we already have Robin and she fits no role.