You can see there are some really small countries with small numbers of jws.
Indeed. There is a poster here, an active JW, who comes from a EU country where the number of congregations is fewer than the digits on your hand. Some months ago, he related a detailed situation, that he was particularly frustrated with, going on in his congregation, and he specifically said he did not want to disclose his country. Not having his country displayed gives him a certain amount of deniability.
Had he known that his country would be displayed, would he have told his story? If he still told his story, would he have changed some of the details to protect his anonymity? If Simon decides to add country flags as a default setting, he's removed that poster's choice, his sense of control over what information is shared, and at worst, jeopardized the poster's anonymity. Do we want to risk outing him?