literally every item in this game is purely cosmetic and expensive and useless yet people buy them.
as much as everyone here wants to see what country everyone else is from (for whatever reason), proxies exist so the flags displayed might not be accurate at all, and the system isn't all that good.
maybe since the icon item is expensive as heck this should be an add-on feature on it? having your icon displayed as your flag would make the item more worth buying than just having it while you're in-game, though i can't help but think that would increase its price. the other options i could think of is having it as a separate customizable item, or paying once per change of flag.