Ever thought your pirate looks bland with the shape and size, well what if you could re-customize you´re pirate? You may only use it once to re-customize you´re pirate. I mean who doesn´t wanna change their pirates look I mean this may not be a game changer but i defiantly think it would be something unique to look upon.
Yeah, this is doable. Fallout 4 had this as a console command and it was extremely helpful, mostly because the player character in Bethesda games never looks the same in the game world as in the creation menu. But honestly I have run into the same problem in POTCO. "Oh no, I didn't mean to make my head so small, or my nose so long, or my height so short."
I think if there are ever plans to change or fix the polygons in the current player model (for instance the space between the head and the hair), that this should be available at least once. This might change the way all pirates look and make some people unhappy without the option to fix it.
Barbers, jewelers, and tailors already manipulate the pirate data, so you could just call the makeapirate GUI instead of the shop GUI. Only problem with that is that it's not lore-friendly at all and might confuse friends if you decide to drastically change your appearance.
Bottom line, I support this idea but only with some restrictions added, like hair, clothes, jewelry, gender, or name. This might mean creating a new separate makeapirate GUI and the developers may not be keen to develop such a thing.