Indeed, Grog is rum without calling it rum for the sake of keeping the game child-friendly. As we all know the word "rum" is much more attributed to pirates than "grog" even though they're essentially the same thing (Grog was simply rum mixed with water and a few spices). Children are unlikely to find the word outside of POTCO, and I can only assume this is intentional. They cover their tracks too, asking the player to recover "grog" from enemies, and perhaps even more prominent, the naming of "Doc Grog," (nickname of Doctor Grogan) and that he's a quest character.
I'm not trying to argue or come off as rude, I just feel that Disney had their reasons for doing certain things. Furthermore, I quite like the usage Disney attributed to the Grog item. I think instead of the absence of grog being a limiting factor that it'd have a much better place in the game as a valuable commodity, as a sort of currency for bartering with craftsmen.
I do like the idea of ship expansion, although I'm not sure if or how much tweaking would be needed for your idea to be a viable option since ships are designed for certain purposes and changing their specifications might offset the balance put in place by Disney.
Sloops are advertised as hit-and-run ships with little cargo space, galleons are slower but can pack (and endure) a heavy punch, and carry much more cargo. Frigates are in the middle, and brigs are intended to be an improvement upon the Frigate. I like the crew idea, but as we saw in older versions of POTCO, too many NPCs out on the high seas causes lots of lag. Perhaps if we could optimize the game for somewhat newer devices we could afford to see them return on our own ships.
But do keep in mind POTCO/TLOPO are social games, and there's a reason for the Crew mechanic. Players can strategize whereas NPCs can merely point and shoot with some random amount of inaccuracy.
Of course, these are all just suggestions.
All just some things to keep in mind.