Jimbie has no reason to join. ALL The Straw Hats joined do to selfish reasons. They all joined for their own sake and because they owe their life to Luffy. That goes the same with all other characters mentioned thus far. They won't join because they don't owe Luffy as much as the rest of the Straw Hats and they don't have any reason to leave where they are now. If anything Luffy owes people like Jimbie and Mr. 2 a life debt and should join them.