Aesthetic purposes? This is interesting as a concept. I do not think it is "ugly" for barbarians to pop-up in a visible square outside your borders. Prevents you from using the game's mechanics to cheat.
The initial notion of "non visible squares outside your territory" didn't mean, "just spam some hawks and some floating eyes, and you get rid of the barbs for the whole game", it meant, "the barbarians will spawn outside your cultural borders, so you can see them coming".
What FF has done is to stay true to the purpose. Barbs spawn outside your territory, and you cannot prevent it exploting the mechanic. You have to deal with them.
As for "wilderness areas". Don't tell me that you consider that new settlement at the borders of your empire an "urbanized" area...It is still wilderness. Everything outside any cultural borders is "wilderness". One square is not an area 100x100 square meters. It is a quite big area.